No MediaQuery widget found.

errorlog

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following assertion was thrown while handling a gesture:
No MediaQuery widget found.

MyApp widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: MyApp
  state: _MyAppState#6b131
The ownership chain for the affected widget is: "MyApp ← [root]"

Typically, the MediaQuery widget is introduced by the MaterialApp or WidgetsApp widget at the top of your application widget tree.

When the exception was thrown, this was the stack: 
#0      debugCheckHasMediaQuery.<anonymous closure> (package:flutter/src/widgets/debug.dart:219:7)
#1      debugCheckHasMediaQuery (package:flutter/src/widgets/debug.dart:231:4)
#2      showModalBottomSheet (package:flutter/src/material/bottom_sheet.dart:529:10)
#3      _MyAppState._pickImage (package:fluttercamera/main.dart:93:5)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:705:14)
...
Handler: "onTap"
Recognizer: TapGestureRecognizer#16761
  debugOwner: GestureDetector
  state: possible
  won arena
  finalPosition: Offset(200.4, 120.3)
  finalLocalPosition: Offset(58.5, 18.3)
  button: 1
  sent tap down
════════════════════════════════════════════════════════════════════════════════════════════════════

main.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:multi_image_picker/multi_image_picker.dart';

void main() => runApp(new MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Asset> images = List<Asset>();
  String _error = 'No Error Dectected';

  @override
  void initState() {
    super.initState();
  }

  Widget buildGridView() {
    return GridView.count(
      crossAxisCount: 3,
      children: List.generate(images.length, (index) {
        Asset asset = images[index];
        return AssetThumb(
          asset: asset,
          width: 300,
          height: 300,
        );
      }),
    );
  }

  Future<void> loadAssets() async {
    List<Asset> resultList = List<Asset>();
    String error = 'No Error Dectected';

    try {
      resultList = await MultiImagePicker.pickImages(
        maxImages: 300,
        enableCamera: true,
        selectedAssets: images,
        cupertinoOptions: CupertinoOptions(takePhotoIcon: "chat"),
        materialOptions: MaterialOptions(
          actionBarColor: "#abcdef",
          actionBarTitle: "Example App",
          allViewTitle: "All Photos",
          useDetailsView: false,
          selectCircleStrokeColor: "#000000",
        ),
      );
    } on Exception catch (e) {
      error = e.toString();
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      images = resultList;
      _error = error;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Column(
          children: <Widget>[
            Center(child: Text('Error: $_error')),
            RaisedButton(
              child: Text("Pick images"),
              onPressed: _pickImage,
            ),
            Expanded(
              child: buildGridView(),
            )
          ],
        ),
      ),
    );
  }

  _pickImage() {
    showModalBottomSheet(
        context: context,
        builder: (context) =>
            Container(
              height: 160,
              child: Column(
                children: <Widget>[_item('拍照', true), _item('相簿', false)],
              ),
            ));
  }

  _item(String title, bool isTakePhoto) {
    return GestureDetector(
      child: ListTile(
        leading: Icon(isTakePhoto ? Icons.camera_alt : Icons.photo_library),
        onTap: () => loadAssets(),
      ),
    );
  }
}