TypeError: Null check operator used on a null value

[sentry-io]

Sentry Issue: GLUT-ASSISTANT-N-3Q

TypeError: Null check operator used on a null value
  File "framework.dart", line 1223, in State.setState
    _element!.markNeedsBuild();
  File "login.dart", line 99, in LoginPageState._codeCheck._next
    setState(() {
  File "login.dart", line 107, in LoginPageState._codeCheck.<T>
    await codeCheck(checkCodeController.text.toString()).then((String value) => _next(value));
  File "zone.dart", line 1407, in _rootRunUnary
  File "zone.dart", line 1405, in _rootRunUnary
...
(2 additional frame(s) were not displayed)

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