MOBILE-4263 quiz: Remove non-null assertions

src/addons/mod/quiz/components/index/index.ts

@@ -333,15 +333,16 @@ export class AddonModQuizIndexComponent extends CoreCourseModuleMainActivityComp
             return;
         }
 
+        const bestGrade = this.bestGrade.grade;
         const formattedGradebookGrade = AddonModQuiz.formatGrade(this.gradebookData.grade, quiz.decimalpoints);
-        const formattedBestGrade = AddonModQuiz.formatGrade(this.bestGrade.grade, quiz.decimalpoints);
+        const formattedBestGrade = AddonModQuiz.formatGrade(bestGrade, quiz.decimalpoints);
         let gradeToShow = formattedGradebookGrade; // By default we show the grade in the gradebook.
 
         this.showResults = true;
         this.gradeOverridden = formattedGradebookGrade != formattedBestGrade;
         this.gradebookFeedback = this.gradebookData.feedback;
 
-        if (this.bestGrade.grade! > this.gradebookData.grade && this.gradebookData.grade == quiz.grade) {
+        if (bestGrade && bestGrade > this.gradebookData.grade && this.gradebookData.grade == quiz.grade) {
             // The best grade is higher than the max grade for the quiz.
             // We'll do like Moodle web and show the best grade instead of the gradebook grade.
             this.gradeOverridden = false;
@@ -556,8 +557,16 @@ export class AddonModQuizIndexComponent extends CoreCourseModuleMainActivityComp
      *
      * @returns Promise resolved when done.
      */
-    protected sync(): Promise<AddonModQuizSyncResult> {
+    protected async sync(): Promise<AddonModQuizSyncResult> {
-        return AddonModQuizSync.syncQuiz(this.candidateQuiz!, true);
+        if (!this.candidateQuiz) {
+            return {
+                warnings: [],
+                attemptFinished: false,
+                updated: false,
+            };
+        }
+
+        return AddonModQuizSync.syncQuiz(this.candidateQuiz, true);
     }
 
     /**
@@ -579,36 +588,31 @@ export class AddonModQuizIndexComponent extends CoreCourseModuleMainActivityComp
         }
 
         const lastFinished = AddonModQuiz.getLastFinishedAttemptFromList(attempts);
-        const promises: Promise<unknown>[] = [];
+        let openReview = false;
 
         if (this.autoReview && lastFinished && lastFinished.id >= this.autoReview.attemptId) {
             // User just finished an attempt in offline and it seems it's been synced, since it's finished in online.
             // Go to the review of this attempt if the user hasn't left this view.
             if (!this.isDestroyed && this.isCurrentView) {
-                promises.push(this.goToAutoReview());
+                openReview = true;
             }
             this.autoReview = undefined;
         }
 
-        // Get combined review options.
+        const [options] = await Promise.all([
-        promises.push(AddonModQuiz.getCombinedReviewOptions(quiz.id, { cmId: this.module.id }).then((options) => {
+            AddonModQuiz.getCombinedReviewOptions(quiz.id, { cmId: this.module.id }),
+            this.getQuizGrade(),
+            openReview ? this.goToAutoReview() : undefined,
+        ]);
+
         this.options = options;
-
-            return;
-        }));
-
-        // Get best grade.
-        promises.push(this.getQuizGrade());
-
-        await Promise.all(promises);
-
         const grade = this.gradebookData?.grade !== undefined ? this.gradebookData.grade : this.bestGrade?.grade;
         const quizGrade = AddonModQuiz.formatGrade(grade, quiz.decimalpoints);
 
         // Calculate data to construct the header of the attempts table.
-        AddonModQuizHelper.setQuizCalculatedData(quiz, this.options!);
+        AddonModQuizHelper.setQuizCalculatedData(quiz, this.options);
 
-        this.overallStats = !!lastFinished && this.options!.alloptions.marks >= AddonModQuizProvider.QUESTION_OPTIONS_MARK_AND_MAX;
+        this.overallStats = !!lastFinished && this.options.alloptions.marks >= AddonModQuizProvider.QUESTION_OPTIONS_MARK_AND_MAX;
 
         // Calculate data to show for each attempt.
         const formattedAttempts = await Promise.all(attempts.map((attempt, index) => {

src/addons/mod/quiz/components/navigation-modal/navigation-modal.ts

@@ -61,6 +61,6 @@ export type AddonModQuizNavigationQuestion = CoreQuestionQuestionParsed & {
 };
 
 export type AddonModQuizNavigationModalReturn = {
-    page?: number;
+    page: number;
     slot?: number;
 };

src/addons/mod/quiz/components/preflight-modal/preflight-modal.ts

@@ -66,11 +66,13 @@ export class AddonModQuizPreflightModalComponent implements OnInit {
         }
 
         try {
+            const quiz = this.quiz;
+
             await Promise.all(this.rules.map(async (rule) => {
                 // Check if preflight is required for rule and, if so, get the component to render it.
                 const required = await AddonModQuizAccessRuleDelegate.isPreflightCheckRequiredForRule(
                     rule,
-                    this.quiz!,
+                    quiz,
                     this.attempt,
                     this.prefetch,
                     this.siteId,

src/addons/mod/quiz/pages/attempt/attempt.page.ts

@@ -94,20 +94,20 @@ export class AddonModQuizAttemptPage implements OnInit {
             // Load attempt data.
             const [options, accessInfo, attempt] = await Promise.all([
                 AddonModQuiz.getCombinedReviewOptions(this.quiz.id, { cmId: this.quiz.coursemodule }),
-                this.fetchAccessInfo(),
+                this.fetchAccessInfo(this.quiz),
-                this.fetchAttempt(),
+                this.fetchAttempt(this.quiz.id),
             ]);
 
             // Set calculated data.
             this.showReviewColumn = accessInfo.canreviewmyattempts;
             AddonModQuizHelper.setQuizCalculatedData(this.quiz, options);
 
-            this.attempt = await AddonModQuizHelper.setAttemptCalculatedData(this.quiz!, attempt, false, undefined, true);
+            this.attempt = await AddonModQuizHelper.setAttemptCalculatedData(this.quiz, attempt, false, undefined, true);
 
             // Check if the feedback should be displayed.
-            const grade = Number(this.attempt!.rescaledGrade);
+            const grade = Number(this.attempt.rescaledGrade);
 
-            if (this.quiz.showFeedbackColumn && AddonModQuiz.isAttemptFinished(this.attempt!.state) &&
+            if (this.quiz.showFeedbackColumn && AddonModQuiz.isAttemptFinished(this.attempt.state) &&
                     options.someoptions.overallfeedback && !isNaN(grade)) {
 
                 // Feedback should be displayed, get the feedback for the grade.
@@ -127,11 +127,12 @@ export class AddonModQuizAttemptPage implements OnInit {
     /**
      * Get the attempt.
      *
+     * @param quizId Quiz ID.
      * @returns Promise resolved when done.
      */
-    protected async fetchAttempt(): Promise<AddonModQuizAttemptWSData> {
+    protected async fetchAttempt(quizId: number): Promise<AddonModQuizAttemptWSData> {
         // Get all the attempts and search the one we want.
-        const attempts = await AddonModQuiz.getUserAttempts(this.quiz!.id, { cmId: this.cmId });
+        const attempts = await AddonModQuiz.getUserAttempts(quizId, { cmId: this.cmId });
 
         const attempt = attempts.find(attempt => attempt.id == this.attemptId);
 
@@ -148,10 +149,11 @@ export class AddonModQuizAttemptPage implements OnInit {
     /**
      * Get the access info.
      *
+     * @param quiz Quiz instance.
      * @returns Promise resolved when done.
      */
-    protected async fetchAccessInfo(): Promise<AddonModQuizGetQuizAccessInformationWSResponse> {
+    protected async fetchAccessInfo(quiz: AddonModQuizQuizData): Promise<AddonModQuizGetQuizAccessInformationWSResponse> {
-        const accessInfo = await AddonModQuiz.getQuizAccessInformation(this.quiz!.id, { cmId: this.cmId });
+        const accessInfo = await AddonModQuiz.getQuizAccessInformation(quiz.id, { cmId: this.cmId });
 
         if (!accessInfo.canreviewmyattempts) {
             return accessInfo;
@@ -161,7 +163,7 @@ export class AddonModQuizAttemptPage implements OnInit {
         await CoreUtils.ignoreErrors(AddonModQuiz.invalidateAttemptReviewForPage(this.attemptId, -1));
 
         try {
-            await AddonModQuiz.getAttemptReview(this.attemptId, { page: -1, cmId: this.quiz!.coursemodule });
+            await AddonModQuiz.getAttemptReview(this.attemptId, { page: -1, cmId: quiz.coursemodule });
         } catch {
             // Error getting the review, assume the user cannot review the attempt.
             accessInfo.canreviewmyattempts = false;
@@ -202,7 +204,11 @@ export class AddonModQuizAttemptPage implements OnInit {
      * @returns Promise resolved when done.
      */
     async reviewAttempt(): Promise<void> {
-        CoreNavigator.navigate(`../../review/${this.attempt!.id}`);
+        if (!this.attempt) {
+            return;
+        }
+
+        CoreNavigator.navigate(`../../review/${this.attempt.id}`);
     }
 
 }

src/addons/mod/quiz/pages/player/player.page.ts

@@ -203,6 +203,10 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @param button Clicked button.
      */
     async behaviourButtonClicked(button: CoreQuestionBehaviourButton): Promise<void> {
+        if (!this.quiz || !this.attempt) {
+            return;
+        }
+
         let modal: CoreIonLoadingElement | undefined;
 
         try {
@@ -212,13 +216,13 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             modal = await CoreDomUtils.showModalLoading('core.sending', true);
 
             // Get the answers.
-            const answers = await this.prepareAnswers();
+            const answers = await this.prepareAnswers(this.quiz.coursemodule);
 
             // Add the clicked button data.
             answers[button.name] = button.value;
 
             // Behaviour checks are always in online.
-            await AddonModQuiz.processAttempt(this.quiz!, this.attempt!, answers, this.preflightData);
+            await AddonModQuiz.processAttempt(this.quiz, this.attempt, answers, this.preflightData);
 
             this.reloadNavigation = true; // Data sent to server, navigation should be reloaded.
 
@@ -230,7 +234,7 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             this.content?.scrollToTop(); // Scroll top so the spinner is seen.
 
             try {
-                await this.loadPage(this.attempt!.currentpage!);
+                await this.loadPage(this.attempt.currentpage ?? 0);
             } finally {
                 this.loaded = true;
                 if (scrollTop != -1) {
@@ -311,8 +315,8 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             }
         } catch (error) {
             // If the user isn't seeing the summary, start the check again.
-            if (!this.showSummary) {
+            if (!this.showSummary && this.quiz) {
-                this.autoSave.startCheckChangesProcess(this.quiz!, this.attempt, this.preflightData, this.offline);
+                this.autoSave.startCheckChangesProcess(this.quiz, this.attempt, this.preflightData, this.offline);
             }
 
             CoreDomUtils.showErrorModalDefault(error, 'addon.mod_quiz.errorgetquestions', true);
@@ -351,7 +355,7 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             this.offline = await AddonModQuiz.isLastAttemptOfflineUnfinished(this.quiz);
         }
 
-        if (this.quiz!.timelimit && this.quiz!.timelimit > 0) {
+        if (this.quiz.timelimit && this.quiz.timelimit > 0) {
             this.readableTimeLimit = CoreTime.formatTime(this.quiz.timelimit);
         }
 
@@ -394,11 +398,15 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     async finishAttempt(userFinish?: boolean, timeUp?: boolean): Promise<void> {
+        if (!this.quiz || !this.attempt) {
+            return;
+        }
+
         let modal: CoreIonLoadingElement | undefined;
 
         try {
             // Show confirm if the user clicked the finish button and the quiz is in progress.
-            if (!timeUp && this.attempt!.state == AddonModQuizProvider.ATTEMPT_IN_PROGRESS) {
+            if (!timeUp && this.attempt.state == AddonModQuizProvider.ATTEMPT_IN_PROGRESS) {
                 await CoreDomUtils.showConfirm(Translate.instant('addon.mod_quiz.confirmclose'));
             }
 
@@ -408,8 +416,8 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
 
             // Trigger an event to notify the attempt was finished.
             CoreEvents.trigger(AddonModQuizProvider.ATTEMPT_FINISHED_EVENT, {
-                quizId: this.quiz!.id,
+                quizId: this.quiz.id,
-                attemptId: this.attempt!.id,
+                attemptId: this.attempt.id,
                 synced: !this.offline,
             }, CoreSites.getCurrentSiteId());
 
@@ -431,9 +439,13 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async fixSequenceChecks(): Promise<void> {
+        if (!this.attempt) {
+            return;
+        }
+
         // Get current page data again to get the latest sequencechecks.
-        const data = await AddonModQuiz.getAttemptData(this.attempt!.id, this.attempt!.currentpage!, this.preflightData, {
+        const data = await AddonModQuiz.getAttemptData(this.attempt.id, this.attempt.currentpage ?? 0, this.preflightData, {
-            cmId: this.quiz!.coursemodule,
+            cmId: this.quiz?.coursemodule,
             readingStrategy: this.offline ? CoreSitesReadingStrategy.PREFER_CACHE : CoreSitesReadingStrategy.ONLY_NETWORK,
         });
 
@@ -465,14 +477,14 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * Initializes the timer if enabled.
      */
     protected initTimer(): void {
-        if (!this.attemptAccessInfo?.endtime || this.attemptAccessInfo.endtime < 0) {
+        if (!this.quizAccessInfo || !this.attempt || !this.attemptAccessInfo?.endtime || this.attemptAccessInfo.endtime < 0) {
             return;
         }
 
         // Quiz has an end time. Check if time left should be shown.
         const shouldShowTime = AddonModQuiz.shouldShowTimeLeft(
-            this.quizAccessInfo!.activerulenames,
+            this.quizAccessInfo.activerulenames,
-            this.attempt!,
+            this.attempt,
             this.attemptAccessInfo.endtime,
         );
 
@@ -490,8 +502,12 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async loadPage(page: number): Promise<void> {
-        const data = await AddonModQuiz.getAttemptData(this.attempt!.id, page, this.preflightData, {
+        if (!this.quiz || !this.attempt) {
-            cmId: this.quiz!.coursemodule,
+            return;
+        }
+
+        const data = await AddonModQuiz.getAttemptData(this.attempt.id, page, this.preflightData, {
+            cmId: this.quiz.coursemodule,
             readingStrategy: this.offline ? CoreSitesReadingStrategy.PREFER_CACHE : CoreSitesReadingStrategy.ONLY_NETWORK,
         });
 
@@ -523,7 +539,7 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
         );
 
         // Start looking for changes.
-        this.autoSave.startCheckChangesProcess(this.quiz!, this.attempt, this.preflightData, this.offline);
+        this.autoSave.startCheckChangesProcess(this.quiz, this.attempt, this.preflightData, this.offline);
     }
 
     /**
@@ -532,23 +548,27 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async loadSummary(): Promise<void> {
+        if (!this.quiz || !this.attempt) {
+            return;
+        }
+
         this.summaryQuestions = [];
 
-        this.summaryQuestions = await AddonModQuiz.getAttemptSummary(this.attempt!.id, this.preflightData, {
+        this.summaryQuestions = await AddonModQuiz.getAttemptSummary(this.attempt.id, this.preflightData, {
-            cmId: this.quiz!.coursemodule,
+            cmId: this.quiz.coursemodule,
             loadLocal: this.offline,
             readingStrategy: this.offline ? CoreSitesReadingStrategy.PREFER_CACHE : CoreSitesReadingStrategy.ONLY_NETWORK,
         });
 
         this.showSummary = true;
-        this.canReturn = this.attempt!.state == AddonModQuizProvider.ATTEMPT_IN_PROGRESS && !this.attempt!.finishedOffline;
+        this.canReturn = this.attempt.state == AddonModQuizProvider.ATTEMPT_IN_PROGRESS && !this.attempt.finishedOffline;
         this.preventSubmitMessages = AddonModQuiz.getPreventSubmitMessages(this.summaryQuestions);
 
-        this.dueDateWarning = AddonModQuiz.getAttemptDueDateWarning(this.quiz!, this.attempt!);
+        this.dueDateWarning = AddonModQuiz.getAttemptDueDateWarning(this.quiz, this.attempt);
 
         // Log summary as viewed.
         CoreUtils.ignoreErrors(
-            AddonModQuiz.logViewAttemptSummary(this.attempt!.id, this.preflightData, this.quiz!.id, this.quiz!.name),
+            AddonModQuiz.logViewAttemptSummary(this.attempt.id, this.preflightData, this.quiz.id, this.quiz.name),
         );
     }
 
@@ -558,9 +578,13 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async loadNavigation(): Promise<void> {
+        if (!this.attempt) {
+            return;
+        }
+
         // We use the attempt summary to build the navigation because it contains all the questions.
-        this.navigation = await AddonModQuiz.getAttemptSummary(this.attempt!.id, this.preflightData, {
+        this.navigation = await AddonModQuiz.getAttemptSummary(this.attempt.id, this.preflightData, {
-            cmId: this.quiz!.coursemodule,
+            cmId: this.quiz?.coursemodule,
             loadLocal: this.offline,
             readingStrategy: this.offline ? CoreSitesReadingStrategy.PREFER_CACHE : CoreSitesReadingStrategy.ONLY_NETWORK,
         });
@@ -602,21 +626,22 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             return;
         }
 
-        this.changePage(modalData.page!, true, modalData.slot);
+        this.changePage(modalData.page, true, modalData.slot);
     }
 
     /**
      * Prepare the answers to be sent for the attempt.
      *
+     * @param componentId Component ID.
      * @returns Promise resolved with the answers.
      */
-    protected prepareAnswers(): Promise<CoreQuestionsAnswers> {
+    protected prepareAnswers(componentId: number): Promise<CoreQuestionsAnswers> {
         return CoreQuestionHelper.prepareAnswers(
             this.questions,
             this.getAnswers(),
             this.offline,
             this.component,
-            this.quiz!.coursemodule,
+            componentId,
         );
     }
 
@@ -629,18 +654,22 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async processAttempt(userFinish?: boolean, timeUp?: boolean, retrying?: boolean): Promise<void> {
+        if (!this.quiz || !this.attempt) {
+            return;
+        }
+
         // Get the answers to send.
         let answers: CoreQuestionsAnswers = {};
 
         if (!this.showSummary) {
-            answers = await this.prepareAnswers();
+            answers = await this.prepareAnswers(this.quiz.coursemodule);
         }
 
         try {
             // Send the answers.
             await AddonModQuiz.processAttempt(
-                this.quiz!,
+                this.quiz,
-                this.attempt!,
+                this.attempt,
                 answers,
                 this.preflightData,
                 userFinish,
@@ -676,7 +705,7 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
             CoreForms.triggerFormSubmittedEvent(this.formElement, !this.offline, CoreSites.getCurrentSiteId());
         }
 
-        return CoreQuestionHelper.clearTmpData(this.questions, this.component, this.quiz!.coursemodule);
+        return CoreQuestionHelper.clearTmpData(this.questions, this.component, this.quiz.coursemodule);
     }
 
     /**
@@ -731,12 +760,16 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
      * @returns Promise resolved when done.
      */
     protected async startOrContinueAttempt(): Promise<void> {
+        if (!this.quiz || !this.quizAccessInfo) {
+            return;
+        }
+
         let attempt = this.newAttempt ? undefined : this.lastAttempt;
 
         // Get the preflight data and start attempt if needed.
         attempt = await AddonModQuizHelper.getAndCheckPreflightData(
-            this.quiz!,
+            this.quiz,
-            this.quizAccessInfo!,
+            this.quizAccessInfo,
             this.preflightData,
             attempt,
             this.offline,
@@ -745,8 +778,8 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
         );
 
         // Re-fetch attempt access information with the right attempt (might have changed because a new attempt was created).
-        this.attemptAccessInfo = await AddonModQuiz.getAttemptAccessInformation(this.quiz!.id, attempt.id, {
+        this.attemptAccessInfo = await AddonModQuiz.getAttemptAccessInformation(this.quiz.id, attempt.id, {
-            cmId: this.quiz!.coursemodule,
+            cmId: this.quiz.coursemodule,
             readingStrategy: this.offline ? CoreSitesReadingStrategy.PREFER_CACHE : CoreSitesReadingStrategy.ONLY_NETWORK,
         });
 
@@ -756,7 +789,7 @@ export class AddonModQuizPlayerPage implements OnInit, OnDestroy, CanLeave {
 
         if (this.attempt.state != AddonModQuizProvider.ATTEMPT_OVERDUE && !this.attempt.finishedOffline) {
             // Attempt not overdue and not finished in offline, load page.
-            await this.loadPage(this.attempt.currentpage!);
+            await this.loadPage(this.attempt.currentpage ?? 0);
 
             this.initTimer();
         } else {

src/addons/mod/quiz/pages/review/review.page.ts

@@ -112,7 +112,7 @@ export class AddonModQuizReviewPage implements OnInit {
      * @param slot Slot of the question to scroll to.
      */
     async changePage(page: number, slot?: number): Promise<void> {
-        if (slot !== undefined && (this.attempt!.currentpage == -1 || page == this.currentPage)) {
+        if (slot !== undefined && (this.attempt?.currentpage == -1 || page == this.currentPage)) {
             // Scrol to a certain question in the current page.
             this.scrollToQuestion(slot);
 
@@ -174,7 +174,7 @@ export class AddonModQuizReviewPage implements OnInit {
      * @returns Promise resolved when done.
      */
     protected async loadPage(page: number): Promise<void> {
-        const data = await AddonModQuiz.getAttemptReview(this.attemptId, { page, cmId: this.quiz!.coursemodule });
+        const data = await AddonModQuiz.getAttemptReview(this.attemptId, { page, cmId: this.quiz?.coursemodule });
 
         this.attempt = data.attempt;
         this.attempt.currentpage = page;
@@ -203,7 +203,7 @@ export class AddonModQuizReviewPage implements OnInit {
      */
     protected async loadNavigation(): Promise<void> {
         // Get all questions in single page to retrieve all the questions.
-        const data = await AddonModQuiz.getAttemptReview(this.attemptId, { page: -1, cmId: this.quiz!.coursemodule });
+        const data = await AddonModQuiz.getAttemptReview(this.attemptId, { page: -1, cmId: this.quiz?.coursemodule });
 
         this.navigation = data.questions;
 
@@ -260,7 +260,7 @@ export class AddonModQuizReviewPage implements OnInit {
             return;
         }
 
-        this.readableState = AddonModQuiz.getAttemptReadableStateName(this.attempt!.state || '');
+        this.readableState = AddonModQuiz.getAttemptReadableStateName(this.attempt.state ?? '');
 
         if (this.attempt.state != AddonModQuizProvider.ATTEMPT_FINISHED) {
             return;
@@ -283,7 +283,7 @@ export class AddonModQuizReviewPage implements OnInit {
         }
 
         // Treat grade.
-        if (this.options!.someoptions.marks >= AddonModQuizProvider.QUESTION_OPTIONS_MARK_AND_MAX &&
+        if (this.options && this.options.someoptions.marks >= AddonModQuizProvider.QUESTION_OPTIONS_MARK_AND_MAX &&
                 AddonModQuiz.quizHasGrades(this.quiz)) {
 
             if (data.grade === null || data.grade === undefined) {
@@ -348,7 +348,7 @@ export class AddonModQuizReviewPage implements OnInit {
             return;
         }
 
-        this.changePage(modalData.page!, modalData.slot);
+        this.changePage(modalData.page, modalData.slot);
     }
 
 }

src/addons/mod/quiz/services/handlers/prefetch.ts

@@ -241,7 +241,7 @@ export class AddonModQuizPrefetchHandlerService extends CoreCourseActivityPrefet
 
         const isLastFinished = !attempts.length || AddonModQuiz.isAttemptFinished(attempts[attempts.length - 1].state);
 
-        return quiz.attempts === 0 || quiz.attempts! > attempts.length || !isLastFinished;
+        return quiz.attempts === 0 || (quiz.attempts ?? 0) > attempts.length || !isLastFinished;
     }
 
     /**
@@ -444,7 +444,7 @@ export class AddonModQuizPrefetchHandlerService extends CoreCourseActivityPrefet
             if (attempt.state == AddonModQuizProvider.ATTEMPT_IN_PROGRESS) {
                 // Get data for each page.
                 promises = promises.concat(pages.map(async (page) => {
-                    if (isSequential && page < attempt.currentpage!) {
+                    if (isSequential && attempt.currentpage && page < attempt.currentpage) {
                         // Sequential quiz, cannot get pages before the current one.
                         return;
                     }

src/addons/mod/quiz/services/handlers/push-click.ts

@@ -43,7 +43,7 @@ export class AddonModQuizPushClickHandlerService implements CorePushNotification
      */
     async handles(notification: AddonModQuizPushNotificationData): Promise<boolean> {
         return CoreUtils.isTrueOrOne(notification.notif) && notification.moodlecomponent == 'mod_quiz' &&
-                this.SUPPORTED_NAMES.indexOf(notification.name!) != -1;
+                this.SUPPORTED_NAMES.indexOf(notification.name ?? '') != -1;
     }
 
     /**

src/addons/mod/quiz/services/quiz-helper.ts

@@ -358,7 +358,7 @@ export class AddonModQuizHelperProvider {
             if (attempt) {
                 if (attempt.state != AddonModQuizProvider.ATTEMPT_OVERDUE && !attempt.finishedOffline) {
                     // We're continuing an attempt. Call getAttemptData to validate the preflight data.
-                    await AddonModQuiz.getAttemptData(attempt.id, attempt.currentpage!, preflightData, modOptions);
+                    await AddonModQuiz.getAttemptData(attempt.id, attempt.currentpage ?? 0, preflightData, modOptions);
 
                     if (offline) {
                         // Get current page stored in local.

src/addons/mod/quiz/services/quiz-offline.ts

@@ -198,11 +198,11 @@ export class AddonModQuizOfflineProvider {
         } else {
             entry = {
                 quizid: quiz.id,
-                userid: attempt.userid!,
+                userid: attempt.userid ?? CoreSites.getCurrentSiteUserId(),
                 id: attempt.id,
                 courseid: quiz.course,
                 timecreated: now,
-                attempt: attempt.attempt!,
+                attempt: attempt.attempt ?? 0,
                 currentpage: attempt.currentpage,
                 timemodified: now,
                 finished: finish ? 1 : 0,
@@ -284,10 +284,12 @@ export class AddonModQuizOfflineProvider {
 
             if (questions[slot]) {
                 if (!questionsWithAnswers[slot]) {
-                    questionsWithAnswers[slot] = questions[slot];
+                    questionsWithAnswers[slot] = {
-                    questionsWithAnswers[slot].answers = {};
+                        ...questions[slot],
+                        answers: {},
+                    };
                 }
-                questionsWithAnswers[slot].answers![nameWithoutPrefix] = answers[name];
+                questionsWithAnswers[slot].answers[nameWithoutPrefix] = answers[name];
             }
         }
 
@@ -295,7 +297,7 @@ export class AddonModQuizOfflineProvider {
         await Promise.all(Object.values(questionsWithAnswers).map(async (question) => {
 
             const state = await CoreQuestionBehaviourDelegate.determineNewState(
-                quiz.preferredbehaviour!,
+                quiz.preferredbehaviour ?? '',
                 AddonModQuizProvider.COMPONENT,
                 attempt.id,
                 question,
@@ -317,7 +319,7 @@ export class AddonModQuizOfflineProvider {
             AddonModQuizProvider.COMPONENT,
             quiz.id,
             attempt.id,
-            attempt.userid!,
+            attempt.userid ?? CoreSites.getCurrentSiteUserId(),
             answers,
             timeMod,
             siteId,
@@ -332,7 +334,7 @@ export class AddonModQuizOfflineProvider {
                     AddonModQuizProvider.COMPONENT,
                     quiz.id,
                     attempt.id,
-                    attempt.userid!,
+                    attempt.userid ?? CoreSites.getCurrentSiteUserId(),
                     question,
                     newStates[slot],
                     siteId,

src/addons/mod/quiz/services/quiz-sync.ts

@@ -305,8 +305,9 @@ export class AddonModQuizSyncProvider extends CoreCourseActivitySyncBaseProvider
 
         // Get all the offline attempts for the quiz. It should always be 0 or 1 attempt
         const offlineAttempts = await AddonModQuizOffline.getQuizAttempts(quiz.id, siteId);
+        const offlineAttempt = offlineAttempts.pop();
 
-        if (!offlineAttempts.length) {
+        if (!offlineAttempt) {
             // Nothing to sync, finish.
             return this.finishSync(siteId, quiz, courseId, warnings);
         }
@@ -316,8 +317,6 @@ export class AddonModQuizSyncProvider extends CoreCourseActivitySyncBaseProvider
             throw new CoreError(Translate.instant('core.cannotconnect'));
         }
 
-        const offlineAttempt = offlineAttempts.pop()!;
-
         // Now get the list of online attempts to make sure this attempt exists and isn't finished.
         const onlineAttempts = await AddonModQuiz.getUserAttempts(quiz.id, modOptions);
 

src/addons/mod/quiz/services/quiz.ts

@@ -290,7 +290,7 @@ export class AddonModQuizProvider {
                 return dueDate * 1000;
 
             case AddonModQuizProvider.ATTEMPT_OVERDUE:
-                return (dueDate + quiz.graceperiod!) * 1000;
+                return (dueDate + (quiz.graceperiod ?? 0)) * 1000;
 
             default:
                 this.logger.warn('Unexpected state when getting due date: ' + attempt.state);
@@ -356,7 +356,7 @@ export class AddonModQuizProvider {
                     Translate.instant('addon.mod_quiz.statefinished'),
                     Translate.instant(
                         'addon.mod_quiz.statefinisheddetails',
-                        { $a: CoreTimeUtils.userDate(attempt.timefinish! * 1000) },
+                        { $a: CoreTimeUtils.userDate((attempt.timefinish ?? 0) * 1000) },
                     ),
                 ];
 
@@ -625,7 +625,7 @@ export class AddonModQuizProvider {
         }
 
         if (quiz.questiondecimalpoints == -1) {
-            return quiz.decimalpoints!;
+            return quiz.decimalpoints ?? 1;
         }
 
         return quiz.questiondecimalpoints;
@@ -1780,7 +1780,7 @@ export class AddonModQuizProvider {
      * @returns Whether quiz is graded.
      */
     quizHasGrades(quiz: AddonModQuizQuizWSData): boolean {
-        return quiz.grade! >= 0.000005 && quiz.sumgrades! >= 0.000005;
+        return (quiz.grade ?? 0) >= 0.000005 && (quiz.sumgrades ?? 0) >= 0.000005;
     }
 
     /**
@@ -1802,8 +1802,8 @@ export class AddonModQuizProvider {
 
         const rawGradeNum = typeof rawGrade == 'string' ? parseFloat(rawGrade) : rawGrade;
         if (rawGradeNum !== undefined && rawGradeNum !== null && !isNaN(rawGradeNum)) {
-            if (quiz.sumgrades! >= 0.000005) {
+            if (quiz.sumgrades && quiz.sumgrades >= 0.000005) {
-                grade = rawGradeNum * quiz.grade! / quiz.sumgrades!;
+                grade = rawGradeNum * (quiz.grade ?? 0) / quiz.sumgrades;
             } else {
                 grade = 0;
             }
@@ -1816,7 +1816,7 @@ export class AddonModQuizProvider {
         if (format === 'question') {
             return this.formatGrade(grade, this.getGradeDecimals(quiz));
         } else if (format) {
-            return this.formatGrade(grade, quiz.decimalpoints!);
+            return this.formatGrade(grade, quiz.decimalpoints ?? 1);
         }
 
         return String(grade);

src/core/features/question/services/behaviour-delegate.ts

@@ -132,5 +132,5 @@ export const CoreQuestionBehaviourDelegate = makeSingleton(CoreQuestionBehaviour
  * Answers classified by question slot.
  */
 export type CoreQuestionQuestionWithAnswers = CoreQuestionQuestionParsed & {
-    answers?: CoreQuestionsAnswers;
+    answers: CoreQuestionsAnswers;
 };