stop method
Implementation
@override
Future<void> stop() async {
try { _oscL?.stop(); } catch (_) {}
try { _oscR?.stop(); } catch (_) {}
_oscL?.disconnect();
_oscR?.disconnect();
_gainL?.disconnect();
_gainR?.disconnect();
_merger?.disconnect();
_masterGain?.disconnect();
_oscL = null;
_oscR = null;
_gainL = null;
_gainR = null;
_merger = null;
_masterGain = null;
_running = false;
}