Crash app when call mjpegView.stopStream()

[DongPhamBK]

For some reason I need to call mjpegView.stopStream() when switching to another camera, but that crashes the app so I don't call mjpegView.startStream() first. Is there a way to avoid crashing the app when calling stopStream()? Or can you use a function to check if the stream is running? Any help would be helpful, thanks!