Merge pull request #1995 from jitsi/fix-local-thumbnail

fix(Filmstrip.js): Make sure the local thumbnail is there

modules/UI/videolayout/Filmstrip.js

 
             promises.push(new Promise(() => {
                 let { localThumb } = this.getThumbs();
-                let height = localThumb.height();
+                let height = localThumb ? localThumb.height() : 0;
                 let fontSize = UIUtil.getIndicatorFontSize(height);
                 this.filmstrip.find('.indicator').animate({
                     fontSize