Exception when clicking outside of an already selected stop area

[7h30n3]

The problem

1. Click on a red stop area (and let it load all markers)
2. Click outside the previously selected stop area (not another stop area)
3. Get the following error:

E/flutter (11710): [ERROR:flutter/shell/common/shell.cc(93)] Dart Unhandled Exception: Null check operator used on a null value, stack trace: #0      QuestionnaireProvider._updateQuestionnaireAnswer (package:open_stop/view_models/questionnaire_provider.dart:170:75)
E/flutter (11710): #1      QuestionnaireProvider.close (package:open_stop/view_models/questionnaire_provider.dart:97:5)
E/flutter (11710): #2      _HomeScreenContentState._onMapTap (package:open_stop/screens/home.dart:427:43)
E/flutter (11710): #3      MapGestureMixin.handleTap (package:flutter_map/src/gestures/gestures.dart:578:21)
E/flutter (11710): #4      _TapPositionDetectorState._postCallback (package:positioned_tap_detector_2/positioned_tap_detector_2.dart:131:15)
E/flutter (11710): #5      _TapPositionDetectorState._onTimeout (package:positioned_tap_detector_2/positioned_tap_detector_2.dart:74:7)
E/flutter (11710): #6      _invokeErrorHandler (dart:async/async_error.dart:45:24)
E/flutter (11710): #7      _HandleErrorStream._handleError (dart:async/stream_pipe.dart:269:9)
E/flutter (11710): #8      _ForwardingStreamSubscription._handleError (dart:async/stream_pipe.dart:157:13)
E/flutter (11710): #9      _RootZone.runBinaryGuarded (dart:async/zone.dart:1630:10)
E/flutter (11710): #10     _BufferingStreamSubscription._sendError.sendError (dart:async/stream_impl.dart:360:15)
E/flutter (11710): #11     _BufferingStreamSubscription._sendError (dart:async/stream_impl.dart:378:7)
E/flutter (11710): #12     _BufferingStreamSubscription._addError (dart:async/stream_impl.dart:280:7)
E/flutter (11710): #13     _SyncStreamControllerDispatch._sendError (dart:async/stream_controller.dart:778:19)
E/flutter (11710): #14     _StreamController._addError (dart:async/stream_controller.dart:656:7)
E/flutter (11710): #15     _StreamController.addError (dart:async/stream_controller.dart:610:5)
E/flutter (11710): #16     Stream.timeout.<anonymous closure> (dart:async/stream.dart:1879:20)
E/flutter (11710): #17     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
E/flutter (11710): #18     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:398:19)
E/flutter (11710): #19     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:429:5)
E/flutter (11710): #20     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)

Which app version do you use?

0.2.0

What operating system do you use?

Android

What operating system version do you use?

12

Additional information

No response