[Crash] Null check operator used on a null value

EdsonBueno / infinite_scroll_pagination

Flutter package to help you lazily load and display pages of items as the user scrolls down your screen.

https://pub.dev/packages/infinite_scroll_pagination

MIT License

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[Crash] Null check operator used on a null value #256

Closed trulykasodiya-hub closed 5 months ago

trulykasodiya-hub commented 1 year ago

PagingController.notifyStatusListeners package:infinite_scroll_pagination/src/core/paging_controller.dart:170 Null check operator used on a null value

0	PagingController.notifyStatusListeners	package:infinite_scroll_pagination/src/core/paging_controller.dart:170
1	PagingController.value=	package:infinite_scroll_pagination/src/core/paging_controller.dart:94
2	PagingController.error=	package:infinite_scroll_pagination/src/core/paging_controller.dart:69
3	_SalesOrdersBodyState._fetchPage	package:mobile/View/Screen/Sales_Order/sales_orders.dart:76

cornetthomas commented 7 months ago

/// Calls all the status listeners.
  ///
  /// If listeners are added or removed during this function, the modifications
  /// will not change which listeners are called during this iteration.
  void notifyStatusListeners(PagingStatus status) {
    assert(_debugAssertNotDisposed());

    if (_statusListeners!.isEmpty) {
      return;
    }

    final localListeners = List<PagingStatusListener>.from(_statusListeners!);
    localListeners.forEach((listener) {
      if (_statusListeners!.contains(listener)) {
        listener(status);
      }
    }

Any reason we should expect _statusListeners to never be null? In case you dispose the paging_controller and a callback still happens this can be null.

It would be safer to use _statusListeners?without any downside here?

cornetthomas commented 7 months ago

I guess it is similar as in #246

cornetthomas commented 7 months ago

@EdsonBueno I created a PR for your review