MOBILE-3040 submission: Fix isSubmissionEmpty logic

src/addon/mod/assign/providers/helper.ts

@@ -193,7 +193,15 @@ export class AddonModAssignHelperProvider {
             return true;
         }
 
-        return !!submission.plugins.find((plugin) => this.submissionDelegate.isPluginEmpty(assign, plugin));
+        for (const plugin of submission.plugins) {
+            // If any plugin is not empty, we consider that the submission is not empty either.
+            if (!this.submissionDelegate.isPluginEmpty(assign, plugin)) {
+                return false;
+            }
+        }
+
+        // If all the plugins were empty (or there were no plugins), we consider the submission to be empty.
+        return true;
     }
 
     /**