stopTimer method
void
stopTimer()
Stop the current timer
Implementation
void stopTimer() {
_timer?.cancel();
_timer = null;
_isRunning = false;
_isPaused = false;
_isVisible = false;
_isFinished = false;
_remaining = Duration.zero;
_totalDuration = Duration.zero;
_config = null;
_clearCallbacks();
_clearError();
notifyListeners();
}