Dart Timer Issue

main.dart

import "dart:async";

class SimpleTimer {
  bool looping = false;
  final int delay;
  
  int _to = 0;
  int _currentCount = 0;
  late Timer _timer;
  final _controller = StreamController<int>();
  
  Stream<int> get onTick => _controller.stream;
  
  SimpleTimer({required this.delay});
  
  void from(int value) {
    _currentCount = value;
  }
  
  void to(int value) {
    _to = value;
    _timer = Timer.periodic(Duration(milliseconds: delay), _tick);
  }
  
  void _tick(Timer timer) {
    if (_currentCount > _to) {
        _timer.cancel();
        return;
    }
    _controller.sink.add(_currentCount);
    _currentCount ++;
  }
  
  int get currentCount => _currentCount;
}

void main() {
  //Usage
  final timer = SimpleTimer(delay: 1000);
  timer.onTick.listen((int currentCount) {
    print("Tick! ${currentCount}");
  });
  
  timer..from(1)..to(20);
  
  /*
  NOTE: After running the app once and the timer starts, hit the RUN button many times.
  It will keep creating new instances of timers instead of stopping the current timers.
  It feels like the RUN button does a Soft Reset instead of a Full Restart.
  */
}