Fixed null pointer exception

app/src/main/java/acr/browser/lightning/fragment/BookmarksFragment.java

@@ -98,10 +98,14 @@ public class BookmarksFragment extends Fragment implements View.OnClickListener,
         return Observable.create(new Action<BookmarkViewAdapter>() {
             @Override
             public void onSubscribe(@NonNull Subscriber<BookmarkViewAdapter> subscriber) {
+                Context context = getContext();
+                if (context != null) {
                     mBookmarkAdapter = new BookmarkViewAdapter(getContext(), mBookmarks);
                     setBookmarkDataSet(mBookmarkManager.getBookmarksFromFolder(null, true), false);
                     subscriber.onNext(mBookmarkAdapter);
                 }
+                subscriber.onComplete();
+            }
         });
     }