[google_maps] Make it clear that GoogleMaps should be used inside of a widget with bounded size

[amreniouinnovent]

I got a crash when I used GoogleMap in Expanded widget
On version google_maps_flutter: ^0.5.20+6

Steps to Reproduce

Just use GoogleMap in Expanded Widget

Expected solution

A better log or updating Readme.

Logs

The log is useless here because it is just a general error flutter plugin error.

[✓] Flutter (Channel beta, v1.8.3, on Mac OS X 10.14.6 18G87, locale en-US)
    • Flutter version 1.8.3 at /Users/lahlou/Development/flutter
    • Framework revision e4ebcdf6f4 (4 weeks ago), 2019-07-27 11:48:24 -0700
    • Engine revision 38ac5f30a7
    • Dart version 2.5.0 (build 2.5.0-dev.1.0 0ca1582afd)

[!] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    • Android SDK at /Users/lahlou/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 29.0.2
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
    ✗ Android license status unknown.
      Try re-installing or updating your Android SDK Manager.
      See https://developer.android.com/studio/#downloads or visit https://flutter.dev/setup/#android-setup for detailed instructions.

[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 10.3, Build version 10G8
    • CocoaPods version 1.6.1

[!] Android Studio (version 3.5)
    • Android Studio at /Applications/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    • Dart plugin version 191.8423
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)

[✓] VS Code (version 1.37.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.3.0

[✓] Connected device (1 available)
    • Android SDK built for x86 64 • emulator-5554 • android-x64 • Android 5.1.1 (API 22) (emulator)

[pedromassangocode]

Still valid today (google_maps_flutter: ^0.5.30). GoogleMaps crash if not set in a sized widget, and the documentation does not state that it should be used inside a sized widget.

We may need to update the documentation of GoogleMaps, specifically in https://github.com/flutter/plugins/tree/master/packages/google_maps_flutter/google_maps_flutter#both

Logs

Launching lib/main.dart on Android SDK built for x86 in debug mode...
Running Gradle task 'assembleDebug'...
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Installing build/app/outputs/flutter-apk/app.apk...
Waiting for Android SDK built for x86 to report its views...
Debug service listening on ws://127.0.0.1:54587/lBrTHvC3aB4=/ws
Syncing files to device Android SDK built for x86...
D/EGL_emulation( 8067): eglMakeCurrent: 0xe090f480: ver 3 0 (tinfo 0xd880f3a0)

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown while looking for parent data.:
Incorrect use of ParentDataWidget.
The following ParentDataWidgets are providing parent data to the same RenderObject:
- Expanded(flex: 1) (typically placed directly inside a Flex widget)
- LayoutId-[<_ScaffoldSlot.body>](id: _ScaffoldSlot.body) (typically placed directly inside a
CustomMultiChildLayout widget)
However, a RenderObject can only receive parent data from at most one ParentDataWidget.
Usually, this indicates that at least one of the offending ParentDataWidgets listed above is not
placed directly inside a compatible ancestor widget.
The ownership chain for the RenderObject that received the parent data was:
  Semantics ← _FocusMarker ← Focus ← AndroidView ← GoogleMap ← Expanded ← _BodyBuilder ← MediaQuery
← LayoutId-[<_ScaffoldSlot.body>] ← CustomMultiChildLayout ← ⋯

When the exception was thrown, this was the stack:
#0      RenderObjectElement._findAncestorParentDataElement.<anonymous closure> (package:flutter/src/widgets/framework.dart:5385:11)
#1      RenderObjectElement._findAncestorParentDataElement (package:flutter/src/widgets/framework.dart:5399:6)
#2      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:5724:61)
#3      RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5420:5)
#4      SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5873:11)
...     Normal element mounting (55 frames)
#59     Element.inflateWidget (package:flutter/src/widgets/framework.dart:3490:14)
#60     MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5991:32)
...     Normal element mounting (210 frames)
#270    Element.inflateWidget (package:flutter/src/widgets/framework.dart:3490:14)
#271    MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5991:32)
...     Normal element mounting (273 frames)
#544    Element.inflateWidget (package:flutter/src/widgets/framework.dart:3490:14)
#545    Element.updateChild (package:flutter/src/widgets/framework.dart:3258:18)
#546    RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1174:16)
#547    RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1145:5)
#548    RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:1087:17)
#549    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2620:19)
#550    RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1086:13)
#551    WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:927:7)
#552    WidgetsBinding.scheduleAttachRootWidget.<anonymous closure> (package:flutter/src/widgets/binding.dart:908:7)
(elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following assertion was thrown while looking for parent data.:
Incorrect use of ParentDataWidget.

The following ParentDataWidgets are providing parent data to the same RenderObject:
- Expanded(flex: 1) (typically placed directly inside a Flex widget)
- LayoutId-[<_ScaffoldSlot.body>](id: _ScaffoldSlot.body) (typically placed directly inside a CustomMultiChildLayout widget)
However, a RenderObject can only receive parent data from at most one ParentDataWidget.

Usually, this indicates that at least one of the offending ParentDataWidgets listed above is not placed directly inside a compatible ancestor widget.

The ownership chain for the RenderObject that received the parent data was:
  Semantics ← _FocusMarker ← Focus ← AndroidView ← GoogleMap ← Expanded ← _BodyBuilder ← MediaQuery ← LayoutId-[<_ScaffoldSlot.body>] ← CustomMultiChildLayout ← ⋯
When the exception was thrown, this was the stack: 
#0      RenderObjectElement._findAncestorParentDataElement.<anonymous closure> (package:flutter/src/widgets/framework.dart:5385:11)
#1      RenderObjectElement._findAncestorParentDataElement (package:flutter/src/widgets/framework.dart:5399:6)
#2      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:5724:61)
#3      RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5420:5)
#4      SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5873:11)
...
════════════════════════════════════════════════════════════════════════════════════════════════════

Another exception was thrown: Incorrect use of ParentDataWidget.

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
Incorrect use of ParentDataWidget.
════════════════════════════════════════════════════════════════════════════════════════════════════

Another exception was thrown: Every child of a RenderCustomMultiChildLayoutBox must have an ID in its parent data.

════════ Exception caught by rendering library ═════════════════════════════════════════════════════
Every child of a RenderCustomMultiChildLayoutBox must have an ID in its parent data.
The following child has no ID: RenderSemanticsAnnotations#7031b NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
  parentData: offset=Offset(0.0, 0.0); id=null
  constraints: MISSING
  size: MISSING
  child: RenderAndroidView#3547a NEEDS-LAYOUT NEEDS-PAINT
    needs compositing
    parentData: <none>
    constraints: MISSING
    semantic boundary
    size: MISSING
The relevant error-causing widget was: 
  Scaffold file:///Users/pedromassango/dev/Projects/triage/flutter_plugin_examples/google_maps_flutter_example/lib/main.dart:39:16
════════════════════════════════════════════════════════════════════════════════════════════════════

[pedromassangocode]

Still valid today as the docs were not updated.