addListener was called on null

[nomadme]

Whenever I ran the controller, it is crashing.

The method 'addListener' was called on null.
Receiver: null
Tried calling: addListener(Closure: () => void from Function '_listener@47216319':.)

in my class:

class Foo extends State<Bar> with TickerProviderStateMixin {
GifController gifController;

 @override
  void initState() {
  ...
    gifController = GifController(vsync: this);
    WidgetsBinding.instance.addPostFrameCallback((_){
      gifController.repeat(min: 0,max: 53,period: Duration(milliseconds: 200));
    });
    super.initState();
  }

...

@override
  Widget build(BuildContext context) {
...
 return Container(
...
 GifImage(
    controller: gifController,
    image: AssetImage("assets/inkman-hour-tick.gif"),
 ),
}
...

[elkhalifte]

i think you are calling adListener before loading GifImage Widget