[RN] Fix pinParticipant if we are not yet in a conference

It may happen that such action is fired while joining.

react/features/base/conference/middleware.js

 function _pinParticipant(store, next, action) {
     const state = store.getState();
     const { conference } = state['features/base/conference'];
+
+    if (!conference) {
+        return next(action);
+    }
+
     const participants = state['features/base/participants'];
     const id = action.participant.id;
     const participantById = getParticipantById(participants, id);
-    let pin;
 
     if (typeof APP !== 'undefined') {
         const pinnedParticipant = getPinnedParticipant(participants);
-        const actionName
-            = action.participant.id ? ACTION_PINNED : ACTION_UNPINNED;
-        const local = (participantById && participantById.local)
+        const actionName = id ? ACTION_PINNED : ACTION_UNPINNED;
+        const local
+            = (participantById && participantById.local)
                 || (!id && pinnedParticipant && pinnedParticipant.local);
 
         sendAnalytics(createPinnedEvent(
             actionName,
             local ? 'local' : id,
             {
-                'participant_count': conference.getParticipantCount(),
-                local
+                local,
+                'participant_count': conference.getParticipantCount()
             }));
-
     }
 
     // The following condition prevents signaling to pin local participant and
     // - If we don't have an ID (i.e. no participant identified by an ID), we
     //   check for local participant. If she's currently pinned, then this
     //   action will unpin her and that's why we won't signal here too.
+    let pin;
+
     if (participantById) {
         pin = !participantById.local && !participantById.isBot;
     } else {
         pin = !localParticipant || !localParticipant.pinned;
     }
     if (pin) {
-
         try {
             conference.pinParticipant(id);
         } catch (err) {