feat: set videoId to '' instead of null on load (#205)

src/editors/data/redux/thunkActions/video.js

@@ -27,7 +27,7 @@ export const loadVideoData = () => (dispatch, getState) => {
   });
 
   dispatch(actions.video.load({
-    videoSource: videoUrl,
+    videoSource: videoUrl || '',
     videoId,
     fallbackVideos,
     allowVideoDownloads: rawVideoData.download_video,
@@ -91,7 +91,7 @@ export const determineVideoSources = ({
     [videoUrl, fallbackVideos] = [html5Sources[0], html5Sources.slice(1)];
   }
   return {
-    videoId: edxVideoId,
+    videoId: edxVideoId || '',
     videoUrl: videoUrl || '',
     fallbackVideos: fallbackVideos || [],
   };

src/editors/data/redux/thunkActions/video.test.js

@@ -181,6 +181,19 @@ describe('video thunkActions', () => {
     const youtubeId = 'yOuTuBEiD';
     const youtubeUrl = `https://youtu.be/${youtubeId}`;
     const html5Sources = ['htmLOne', 'hTMlTwo', 'htMLthrEE'];
+    describe('when edx id, youtube id and source values are null', () => {
+      it('returns empty strings for ids and an empty array for sources', () => {
+        expect(thunkActions.determineVideoSources({
+          edxVideoId: null,
+          youtubeId: null,
+          html5Sources: null,
+        })).toEqual({
+          videoUrl: '',
+          videoId: '',
+          fallbackVideos: [],
+        });
+      });
+    });
     describe('when there is an edx video id, youtube id and html5 sources', () => {
       it('returns all three with the youtube id wrapped in url', () => {
         expect(thunkActions.determineVideoSources({