Fix Walkie-Talkie mode in Safari

We didn't check whether we actually had a video device when seeing
if the current video devices was in the list of devices, so this
caused loops which confused Safari.

src/settings/useMediaHandler.tsx

@@ -160,7 +160,7 @@ export function MediaHandlerProvider({ client, children }: Props): JSX.Element {
 
         if (
           // @ts-ignore
-          mediaHandler.videoInput !== videoInput ||
+          (mediaHandler.videoInput && mediaHandler.videoInput !== videoInput) ||
           // @ts-ignore
           mediaHandler.audioInput !== audioInput
         ) {