Not working, got red screen

[b4d4]

Flutter version: 1.20.4
SO: W10 x64

Got this trace:
I/flutter (28331): The following NoSuchMethodError was thrown building HomeScreen(dirty, dependencies: [MediaQuery], I/flutter (28331): state: _HomeScreenState#1c7c2): I/flutter (28331): The getter 'length' was called on null. I/flutter (28331): Receiver: null I/flutter (28331): Tried calling: length I/flutter (28331): I/flutter (28331): The relevant error-causing widget was: I/flutter (28331): HomeScreen I/flutter (28331): file:///E:/bada/Documents/FAUSI/FLUTTER/OCTUBRE%202020/Flutter_medical/lib/main.dart:64:30 I/flutter (28331): I/flutter (28331): When the exception was thrown, this was the stack: I/flutter (28331): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5) I/flutter (28331): #1 titleCase (package:flutter_medical/widgets.dart:369:12) I/flutter (28331): #2 _HomeScreenState.build (package:flutter_medical/routes/home.dart:415:50) I/flutter (28331): #3 StatefulElement.build (package:flutter/src/widgets/framework.dart:4744:28) I/flutter (28331): #4 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4627:15) I/flutter (28331): #5 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4800:11) I/flutter (28331): #6 Element.rebuild (package:flutter/src/widgets/framework.dart:4343:5) I/flutter (28331): #7 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2730:33) I/flutter (28331): #8 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:913:20) I/flutter (28331): #9 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:302:5) I/flutter (28331): #10 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1117:15) I/flutter (28331): #11 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1055:9) I/flutter (28331): #12 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:971:5) I/flutter (28331): #16 _invoke (dart:ui/hooks.dart:251:10) I/flutter (28331): #17 _drawFrame (dart:ui/hooks.dart:209:3) I/flutter (28331): (elided 3 frames from dart:async) I/flutter (28331): I/flutter (28331): ════════════════════════════════════════════════════════════════════════════════════════════════════ I/flutter (28331): Instance of 'QuerySnapshot' I/flutter (28331): worked I/flutter (28331): Instance of 'QuerySnapshot' I/flutter (28331): Instance of 'QuerySnapshot' I/flutter (28331): Another exception was thrown: NoSuchMethodError: The getter 'length' was called on null.

[saad0259]

@b4d4 found any solution?