GoogleMap 在显示地图之前显示红色错误框

在显示地图之前，会显示一个红色的错误窗口 FOR A LONG TIME，然后显示地图。为什么？下面是完整的代码和截图。

主要.dart

import 'dart:async';

import 'package:flutter/material.dart';

import 'package:google_maps_flutter/google_maps_flutter.dart';

import 'package:geolocator/geolocator.dart';

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

class MyApp extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return MaterialApp(
   debugShowCheckedModeBanner: false,
   title: 'Name App',
   theme: ThemeData(
    primarySwatch: Colors.blue,
   ),
   home: Scaffold(
    appBar: AppBar(
     title: Text('Name Page'),
    ),
    body: MyHomePage(),
   ),
  );
 }
}

class MyHomePage extends StatefulWidget {
 @override
 _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

 Completer<GoogleMapController> _controller = Completer();

 //GoogleMapController _controller;

 Position _position;

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

 }

 @override
 void dispose() {
  super.dispose();

 }

 void _f1() {
  setState(() {

  });
 }

 _getPosition() async {
  Position position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.best);
  setState(() {
   _position = position;
  });
 }

 @override
 Widget build(BuildContext context) {
  return Stack(
   children: [
    GoogleMap(
     initialCameraPosition: CameraPosition(
      target: LatLng(_position.latitude, _position.longitude),
      zoom: 19.151926040649414,
      bearing: 222.8334901395799,
     ),
     mapType: MapType.hybrid,
     onMapCreated: (GoogleMapController controller) {
      _controller.complete(controller);
      //_controller = controller;
     },
    ),
    Align(
     alignment: Alignment(0.0, -0.85),
     child: Text(
      '${_position.latitude}\n${_position.longitude}',
      style: TextStyle(
       fontSize: 20.0,
       color: Colors.deepOrange,
      ),
     ),
    ),
    Align(
     alignment: Alignment(0.0, 0.95),
     child: Container(
      //width: double.infinity,
      height: 35.0,
      decoration: BoxDecoration(
       border: Border.all(
        width: 1.0,
        color: Colors.deepOrange,
       ),
       borderRadius: BorderRadius.all(
        Radius.circular(15.0)
       ),
      ),
      child: FlatButton.icon(
       onPressed: () {},
       splashColor: Colors.blue.withOpacity(0.5),
       icon: Icon(
        Icons.directions_boat,
        size: 20.0,
        color: Colors.deepOrange,
       ),
       label: Text(
        'Go to back!',
        style: TextStyle(
         fontSize: 18.0,
         color: Colors.deepOrange,
        ),
       ),
      ),
     ),
    ),
   ],
  );
 }

}