NoSuchMethodError: The method 'call' was called on null

[boozy-ph]

What's the fix for this issue?

E/flutter ( 8587): [ERROR:flutter/lib/ui/ui_dart_state.cc(144)] Unhandled Exception: NoSuchMethodError: The method 'call' was called on null.
E/flutter ( 8587): Receiver: null
E/flutter ( 8587): Tried calling: call()
�[38;5;244mE/flutter ( 8587): #0      Object.noSuchMethod  (dart:core-patch/object_patch.dart:51:5)�[39;49m
�[38;5;248mE/flutter ( 8587): #1      new RxCommandListener.<anonymous closure>�[39;49m
�[38;5;244mE/flutter ( 8587): #2      _rootRunUnary  (dart:async/zone.dart:1132:38)�[39;49m
�[38;5;244mE/flutter ( 8587): #3      _CustomZone.runUnary  (dart:async/zone.dart:1029:19)�[39;49m
�[38;5;244mE/flutter ( 8587): #4      _CustomZone.runUnaryGuarded  (dart:async/zone.dart:931:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #5      _BufferingStreamSubscription._sendData  (dart:async/stream_impl.dart:336:11)�[39;49m
�[38;5;244mE/flutter ( 8587): #6      _BufferingStreamSubscription._add  (dart:async/stream_impl.dart:263:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #7      _ForwardingStreamSubscription._add  (dart:async/stream_pipe.dart:132:11)�[39;49m
�[38;5;244mE/flutter ( 8587): #8      _DistinctStream._handleData  (dart:async/stream_pipe.dart:480:12)�[39;49m
�[38;5;244mE/flutter ( 8587): #9      _ForwardingStreamSubscription._handleData  (dart:async/stream_pipe.dart:164:13)�[39;49m
�[38;5;244mE/flutter ( 8587): #10     _rootRunUnary  (dart:async/zone.dart:1132:38)�[39;49m
�[38;5;244mE/flutter ( 8587): #11     _CustomZone.runUnary  (dart:async/zone.dart:1029:19)�[39;49m
�[38;5;244mE/flutter ( 8587): #12     _CustomZone.runUnaryGuarded  (dart:async/zone.dart:931:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #13     _BufferingStreamSubscription._sendData  (dart:async/stream_impl.dart:336:11)�[39;49m
�[38;5;244mE/flutter ( 8587): #14     _DelayedData.perform  (dart:async/stream_impl.dart:591:14)�[39;49m
�[38;5;244mE/flutter ( 8587): #15     _StreamImplEvents.handleNext  (dart:async/stream_impl.dart:707:11)�[39;49m
�[38;5;244mE/flutter ( 8587): #16     _PendingEvents.schedule.<anonymous closure>  (dart:async/stream_impl.dart:667:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #17     _rootRun  (dart:async/zone.dart:1120:38)�[39;49m
�[38;5;244mE/flutter ( 8587): #18     _CustomZone.run  (dart:async/zone.dart:1021:19)�[39;49m
�[38;5;244mE/flutter ( 8587): #19     _CustomZone.runGuarded  (dart:async/zone.dart:923:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #20     _CustomZone.bindCallbackGuarded.<anonymous closure>  (dart:async/zone.dart:963:23)�[39;49m
�[38;5;244mE/flutter ( 8587): #21     _rootRun  (dart:async/zone.dart:1124:13)�[39;49m
�[38;5;244mE/flutter ( 8587): #22     _CustomZone.run  (dart:async/zone.dart:1021:19)�[39;49m
�[38;5;244mE/flutter ( 8587): #23     _CustomZone.runGuarded  (dart:async/zone.dart:923:7)�[39;49m
�[38;5;244mE/flutter ( 8587): #24     _CustomZone.bindCallbackGuarded.<anonymous closure>  (dart:async/zone.dart:963:23)�[39;49m
�[38;5;244mE/flutter ( 8587): #25     _microtaskLoop  (dart:async/schedule_microtask.dart:41:21)�[39;49m
�[38;5;244mE/flutter ( 8587): #26     _startMicrotaskLoop  (dart:async/schedule_microtask.dart:50:5)�[39;49m

This is about RxCommandListener that was called on widget initState.

_searchLocationCommandListener = RxCommandListener(
          sl<LocationsManager>().updateLocationsCommand, onIsBusy: () {
        setState(() {
          _stackToView = 3;
        });
      }, onResult: (result) {
        if (result.hasData) {
          setState(() {
            _data = result.data;

            if (_data.isNotEmpty) {
              _stackToView = 1;
            } else {
              _stackToView = 2;
            }
          });
        }
      }, onError: (error) {
        print('error $error');
      });

[escamoteur]

Hmm,
the message looks like your RxCommand was null when you tried to call it but the stacktrace has the RxCommandListener somehow in it.
Could you activate 'Break on all Exceptions in your debugger' and try to figure out where it exactly happens?

[freeman29]

This happens on widget initialisation state, and I manage to fix the error by adding the following code/method on RxCommandListener:

onNotBusy: () {
   print('onNotBusy');
}

@escamoteur can you please explain why? was onNotBusy a required one?

[escamoteur]

It's a bug. The moment you set onBusy() it required also onNonBusy. I'm just fixing it

[escamoteur]

Fixed in V4.3.3

Was a bug that only could happen if you only set one of the busy handlers.