Web Validation - Cannot read property 'Symbol(dartx.length)' of null

[jaxnz]

Getting this error on Flutter Web with basic TextField form validation - had it for a while, but just removed validation for development.

Flutter 1.19.0-2.0.pre.214 • channel master • https://github.com/flutter/flutter.git
Framework • revision 1d395c5e18 (9 hours ago) • 2020-05-31 07:41:50 -0700
Engine • revision 923687f0e7
Tools • Dart 2.9.0 (build 2.9.0-13.0.dev 6489a0c68d)

TypeError: Cannot read property 'Symbol(dartx.length)' of null
    at http://localhost:49347/packages/flutter_form_builder/src/fields/form_builder_image_picker.dart.lib.js:10774:66
    at text_form_field._TextFormFieldState.new.[_validate] (http://localhost:49347/packages/flutter/src/widgets/form.dart.lib.js:446:151)
    at http://localhost:49347/packages/flutter/src/widgets/form.dart.lib.js:440:26
    at text_form_field._TextFormFieldState.new.setState (http://localhost:49347/packages/flutter/src/widgets/widget_span.dart.lib.js:14710:22)
    at text_form_field._TextFormFieldState.new.validate (http://localhost:49347/packages/flutter/src/widgets/form.dart.lib.js:439:14)
    at form.FormState.new.[_validate] (http://localhost:49347/packages/flutter/src/widgets/form.dart.lib.js:226:37)
    at form.FormState.new.validate (http://localhost:49347/packages/flutter/src/widgets/form.dart.lib.js:221:29)
    at form_builder.FormBuilderState.new.saveAndValidate (http://localhost:49347/packages/flutter_form_builder/src/form_builder.dart.lib.js:247:42)
    at enquiry_form._EnquiryFormState.new.<anonymous> (http://localhost:49347/packages/webenrol/shared/widgets/form/day_selection.dart.lib.js:3389:77)
    at Generator.next (<anonymous>)
    at runBody (http://localhost:49347/dart_sdk.js:35674:34)
    at Object._async [as async] (http://localhost:49347/dart_sdk.js:35702:7)
    at ink_well.InkWell.new.<anonymous> (http://localhost:49347/packages/webenrol/shared/widgets/form/day_selection.dart.lib.js:3388:436)
    at _InkResponseState.new.[_handleTap] (http://localhost:49347/packages/flutter/src/material/icon_button.dart.lib.js:43158:23)
    at http://localhost:49347/packages/flutter/src/material/icon_button.dart.lib.js:43234:634
    at tap.TapGestureRecognizer.new.invokeCallback (http://localhost:49347/packages/flutter/src/gestures/recognizer.dart.lib.js:191:18)
    at tap.TapGestureRecognizer.new.handleTapUp (http://localhost:49347/packages/flutter/src/gestures/tap.dart.lib.js:355:40)
    at tap.TapGestureRecognizer.new.[_checkUp] (http://localhost:49347/packages/flutter/src/gestures/tap.dart.lib.js:186:12)
    at tap.TapGestureRecognizer.new.acceptGesture (http://localhost:49347/packages/flutter/src/gestures/tap.dart.lib.js:164:23)
    at arena.GestureArenaManager.new.sweep (http://localhost:49347/packages/flutter/src/gestures/arena.dart.lib.js:201:31)
    at binding$5.WidgetsFlutterBinding.new.handleEvent (http://localhost:49347/packages/flutter/src/gestures/binding.dart.lib.js:170:27)
    at binding$5.WidgetsFlutterBinding.new.dispatchEvent (http://localhost:49347/packages/flutter/src/gestures/binding.dart.lib.js:154:24)
    at binding$5.WidgetsFlutterBinding.new.[_handlePointerEvent] (http://localhost:49347/packages/flutter/src/gestures/binding.dart.lib.js:131:14)
    at binding$5.WidgetsFlutterBinding.new.[_flushPointerEventQueue] (http://localhost:49347/packages/flutter/src/gestures/binding.dart.lib.js:105:34)
    at binding$5.WidgetsFlutterBinding.new.[_handlePointerDataPacket] (http://localhost:49347/packages/flutter/src/gestures/binding.dart.lib.js:96:65)
    at Object._invoke1 (http://localhost:49347/dart_sdk.js:159738:7)
    at _engine.EngineWindow.new.invokeOnPointerDataPacket (http://localhost:49347/dart_sdk.js:156917:15)
    at _engine.PointerBinding.__.[_onPointerData] (http://localhost:49347/dart_sdk.js:137115:24)
    at http://localhost:49347/dart_sdk.js:137457:26
    at http://localhost:49347/dart_sdk.js:137422:16

[danvick]

Hi @jaxnz,
Are you sure that the issue comes from this package? We aren't using dartx package directly in this repo.
My knowledge of Flutter Web is a bit limited though.

[jaxnz]

Turns out it was a re-usable widget I had created to use as a Textarea.. have reverted back to using a FormBuilderTextField

class CustomTextArea extends StatelessWidget {
  final int minLines;
  final List<FormFieldValidator> validators;
  final String label;
  final String initialValue;
  final bool readOnly;
  final double textSize;
  CustomTextArea({this.minLines = 5, this.label, this.initialValue, this.readOnly = false, this.textSize = 17, this.validators});
  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.only(top: 10, bottom: 10),
      child: FormBuilderTextField(
        readOnly: readOnly,
        initialValue: initialValue,
        attribute: label,
        minLines: minLines,
        decoration: InputDecoration(
          labelStyle: TextStyle(fontSize: textSize),
          enabledBorder: OutlineInputBorder(
            borderSide: BorderSide(color: Colors.grey[300]),
          ),
          border: OutlineInputBorder(),
          labelText: label,
          alignLabelWithHint: true,
        ),
        validators: validators,
      ),
    );
  }
}