Fix the FlipperArray creation of events

Summary:
The FlipperArray creation from JSONArray used to create an array of `null`'s instead of the FlipperObject, which used to crash the Flipper. Thus added a check in the flipper to not crash in the case when it receives array of nulls. Also fixed the Fresco plugin in mobile to send the proper FlipperArray.

Bug:

{F160049909}

Reviewed By: passy

Differential Revision: D15608297

fbshipit-source-id: 625e017d3bce4135ac699ee5aee8d871db378749

src/plugins/fresco/index.js

@@ -105,8 +105,15 @@ export default class extends FlipperPlugin<PluginState, *, PersistedState> {
       };
 
       events.forEach((event: ImageEventWithId, index) => {
+        if (!event) {
+          return;
+        }
         const {attribution} = event;
-        if (attribution instanceof Array && attribution.length > 0) {
+        if (
+          attribution &&
+          attribution instanceof Array &&
+          attribution.length > 0
+        ) {
           const surface = attribution[0].trim();
           if (surface.length > 0) {
             pluginData.surfaceList.add(surface);