I have a very simple setup involving AVAudioEngine, and a player node, AVAudioPlayerNode.The player node is attached to the audio engine, then connected to the engine's main mixer node.Then, to start outputing some sound, I start the engine, and finally play the node :NSError* err = nil; BOOL started = [_audioEngine startAndReturnError:&err]; if(started) { [_playerNode play]; } else { // handle error }It happens sometimes, the app crashes (on the call to the play function) because, as the system says : "player started when engine not running".I can't understand how this can happen, at least in the code above.No error is returned in `err`.Does somebody knows what happen or faced such a situation ?