MOBILE-3213 scorm: Fix unzip using emulator

src/core/emulator/providers/zip.ts

@@ -88,7 +88,7 @@ export class ZipMock extends Zip {
             const destParent = destination.substring(0, source.lastIndexOf('/')),
                 destFolderName = destination.substr(source.lastIndexOf('/') + 1);
 
-            return this.file.createDir(destParent, destFolderName, false);
+            return this.file.createDir(destParent, destFolderName, true);
         }).then(() => {
 
             const promises = [],

src/providers/file.ts

@@ -1017,7 +1017,7 @@ export class CoreFileProvider {
             return this.zip.unzip(fileEntry.toURL(), destFolder, onProgress);
         }).then((result) => {
             if (result == -1) {
-                return Promise.reject(null);
+                return Promise.reject('Unzip failed.');
             }
         });
     }