Example code does not work: No MediaQuery widget ancestor found.

[LostInDarkMath]

Logs

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======== Exception caught by widgets library =======================================================
The following assertion was thrown building PersistentKeyboardHeightProvider(dirty, state: _PersistentKeyboardHeightProviderState#2ebf7):
No MediaQuery widget ancestor found.

PersistentKeyboardHeightProvider widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: PersistentKeyboardHeightProvider
  dirty
  state: _PersistentKeyboardHeightProviderState#2ebf7
The ownership chain for the affected widget is: "PersistentKeyboardHeightProvider ← MyApp ← [root]"

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.

The relevant error-causing widget was: 
  PersistentKeyboardHeightProvider PersistentKeyboardHeightProvider:file:///E:/Projekte/untitled2/lib/main.dart:14:18
When the exception was thrown, this was the stack: 
#0      debugCheckHasMediaQuery.<anonymous closure> (package:flutter/src/widgets/debug.dart:230:7)
#1      debugCheckHasMediaQuery (package:flutter/src/widgets/debug.dart:245:4)
#2      MediaQuery.of (package:flutter/src/widgets/media_query.dart:859:12)
#3      _PersistentKeyboardHeightProviderState.build (package:flutter_persistent_keyboard_height/src/persistent_keyboard_height_provider.dart:104:32)
#4      StatefulElement.build (package:flutter/src/widgets/framework.dart:4870:27)
#5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4754:15)
#6      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4928:11)
#7      Element.rebuild (package:flutter/src/widgets/framework.dart:4477:5)
#8      ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4735:5)
#9      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4919:11)
#10     ComponentElement.mount (package:flutter/src/widgets/framework.dart:4729:5)
...     Normal element mounting (7 frames)
#17     Element.inflateWidget (package:flutter/src/widgets/framework.dart:3790:14)
#18     Element.updateChild (package:flutter/src/widgets/framework.dart:3540:18)
#19     RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1198:16)
#20     RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1167:5)
#21     RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:1112:18)
#22     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2600:19)
#23     RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1111:13)
#24     WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:944:7)
#25     WidgetsBinding.scheduleAttachRootWidget.<anonymous closure> (package:flutter/src/widgets/binding.dart:924:7)
(elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
====================================================================================================

======== Exception caught by widgets library =======================================================
The following assertion was thrown building PersistentKeyboardHeightProvider(dirty, state: _PersistentKeyboardHeightProviderState#2ebf7):
No MediaQuery widget ancestor found.

PersistentKeyboardHeightProvider widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: PersistentKeyboardHeightProvider
  dirty
  state: _PersistentKeyboardHeightProviderState#2ebf7
The ownership chain for the affected widget is: "PersistentKeyboardHeightProvider ← MyApp ← [root]"

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.

The relevant error-causing widget was: 
  PersistentKeyboardHeightProvider PersistentKeyboardHeightProvider:file:///E:/Projekte/untitled2/lib/main.dart:14:18
When the exception was thrown, this was the stack: 
#0      debugCheckHasMediaQuery.<anonymous closure> (package:flutter/src/widgets/debug.dart:230:7)
#1      debugCheckHasMediaQuery (package:flutter/src/widgets/debug.dart:245:4)
#2      MediaQuery.of (package:flutter/src/widgets/media_query.dart:859:12)
#3      _PersistentKeyboardHeightProviderState.build (package:flutter_persistent_keyboard_height/src/persistent_keyboard_height_provider.dart:104:32)
#4      StatefulElement.build (package:flutter/src/widgets/framework.dart:4870:27)
#5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4754:15)
#6      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4928:11)
#7      Element.rebuild (package:flutter/src/widgets/framework.dart:4477:5)
#8      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2659:19)
#9      WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:882:21)
#10     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5)
#11     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#12     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1081:9)
#13     SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:862:7)
(elided 4 frames from class _RawReceivePortImpl, class _Timer, and dart:async-patch)
====================================================================================================
I/flutter ( 8532): INFO: PeriodicBackgroundTask: 2022-03-11 22:19:30.501332: PeriodicBackgroundService crash_reporter
I/flutter ( 8532): FINE: Controller: 2022-03-11 22:19:30.502671: sendCrashReport

Code

The code is exactly your example:

import 'package:flutter/material.dart';

import 'package:flutter_persistent_keyboard_height/flutter_persistent_keyboard_height.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const PersistentKeyboardHeightProvider(
      child: MaterialApp(
        title: 'Flutter Persistent Keyboard Height Example',
        home: FlutterPersistentKeyboardHeightExample(),
      ),
    );
  }
}

class FlutterPersistentKeyboardHeightExample extends StatelessWidget {
  const FlutterPersistentKeyboardHeightExample({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final keyboardHeight = PersistentKeyboardHeight.of(context).keyboardHeight;

    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          const Padding(
            padding: EdgeInsets.all(16.0),
            child: TextField(
              decoration: InputDecoration(
                labelText: 'Flutter Persistent Keyboard Size Example',
              ),
            ),
          ),
          const SizedBox(height: 8),
          Text('Keyboard height: $keyboardHeight'),
        ],
      ),
    );
  }
}

I use Flutter 2.10.

[f-person]

Thank you for the report! It's fixed now :)