fix switchMedia: stop previous track before switch

[manhere]

manually emit the event, some webview implement (firefox, android...) doesn't fire track-ended event, most common error thrown as "Could not start video source"

[manhere]

related explanation Why is the 'ended' event not firing for this MediaStreamTrack?

[holtwick]

Thanks @manhere I will look at it later today. Indeed, the last remaining issues are about video input. FYI extract from Sentry logging of the current active version:

[holtwick]

Thanks to your fix, we are now crash free 👍