Merge branch 'fix-room-extension-error' into 'master'

Fix if statement for when comment extensions aren't available

See merge request swtp-2019/arsnova-lite!42

src/app/components/shared/comment-list/comment-list.component.ts

@@ -73,7 +73,7 @@ export class CommentListComponent implements OnInit {
 
   getCommentsCreator(): Comment[] {
     let commentThreshold = -10;
-    if (this.room.extensions) {
+    if (this.room.extensions && this.room.extensions['comments']) {
       commentThreshold = this.room.extensions['comments'].commentThreshold;
       if (this.hideCommentsList) {
         return this.filteredComments.filter( x => x.score >= commentThreshold );