feat(call-integration): revert changes related to visitors (jitsi#14150)

* feat(mobile/call-integration): removed undefined checks

react/features/mobile/call-integration/middleware.ts

@@ -154,10 +154,11 @@ function _conferenceFailed({ getState }: IStore, next: Function, action: AnyActi
     // prevented the user from joining a specific conference but the app may be
     // able to eventually join the conference.
     if (!action.error.recoverable) {
+        const { callUUID } = action.conference;
 
-        if (action?.conference?.callUUID) {
+        if (callUUID) {
             delete action.conference.callUUID;
-            CallIntegration.reportCallFailed(action.conference.callUUIDID);
+            CallIntegration.reportCallFailed(callUUID);
         }
     }
 
@@ -184,9 +185,9 @@ function _conferenceJoined({ getState }: IStore, next: Function, action: AnyActi
         return result;
     }
 
-    if (action?.conference?.callUUID) {
-        const { callUUID } = action.conference;
+    const { callUUID } = action.conference;
 
+    if (callUUID) {
         CallIntegration.reportConnectedOutgoingCall(callUUID)
             .then(() => {
                 // iOS 13 doesn't like the mute state to be false before the call is started
@@ -229,9 +230,11 @@ function _conferenceLeft({ getState }: IStore, next: Function, action: AnyAction
         return result;
     }
 
-    if (action?.conference?.callUUID) {
+    const { callUUID } = action.conference;
+
+    if (callUUID) {
         delete action.conference.callUUID;
-        CallIntegration.endCall(action.conference.callUUID);
+        CallIntegration.endCall(callUUID);
     }
 
     return result;
@@ -270,7 +273,7 @@ function _conferenceWillJoin({ dispatch, getState }: IStore, next: Function, act
     }
 
     // When assigning the call UUID, do so in upper case, since iOS will return
-    // it upper cased.
+    // it upper-cased.
     conference.callUUID = (callUUID || uuidv4()).toUpperCase();
 
     CallIntegration.startCall(conference.callUUID, handle, hasVideo)