Not work in GetMaterialApp?

[taosimple]

Init in GetMaterialApp

GetMaterialApp(
      debugShowCheckedModeBanner: false,
      onInit: () async {
        ToastContext().init(context);
      },
      home: HomePage(),
      routes: {
          PAGE_BACKUP: (context) => BackupPage(),
      },
      navigatorObservers: [firebase],
    );

show:
Toast.show('subtype_name_repeated', gravity: Toast.top);

error:

I/flutter ( 9542): #0      Overlay.of.<anonymous closure> (package:flutter/src/widgets/overlay.dart:476:9)
I/flutter ( 9542): #1      Overlay.of (package:flutter/src/widgets/overlay.dart:479:6)
I/flutter ( 9542): #2      ToastView.createView (package:toast/toast.dart:97:28)
I/flutter ( 9542): #3      Toast.show (package:toast/toast.dart:68:17)
I/flutter ( 9542): #4      CreatePatternSheet._checkIntegrity (package:easy_table/pages/sheet/create_pattern_sheet.dart:86:15)
I/flutter ( 9542): #5      CreatePatternSheet.onActionClick (package:easy_table/pages/sheet/create_pattern_sheet.dart:65:15)
I/flutter ( 9542): #6      ShellController.onInit.<anonymous closure> (package:easy_table/widget/bottom_sheet/bottom_sheet_shell.dart:201:34)
I/flutter ( 9542): #7      EventBus.emit (package:easy_table/event/event_bus.dart:37:14)
I/flutter ( 9542): #8      _BottomSheetShellState.buildTitleBar.<anonymous closure> (package:easy_table/widget/bottom_sheet/bottom_sheet_shell.dart:172:41)
I/flutter ( 9542): #9      _InkResponseState.handleTap (package:flutter/src/material/ink_well.dart:1154:21)
I/flutter ( 9542): #10     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:275:24)
I/flutter ( 9542): #11     TapGestureRecogni