VM snapshot must be valid. Check

Add flutter to exiting app project crash

VM snapshot must be valid.
Check failed: vm. Must be able to initialize the VM.

本人Flutter菜鸟遵照官方指式，试着在已有的一个Android项目中添加Flutter Module，但是很不幸的失败了，log给予了我以上的信息，大意是虚拟无法初始化了。问题是我啥也没有干啊。添加Flutter到已有的项目怎么就crash了呢。
所以这一天就这么丧的开始了。

所以我开始Google了，搜了一下在issues里面看到这么一条，
https://github.com/flutter/flutter/issues/19818。

@kimlet is right. The main reason for E/flutter: [ERROR:flutter/runtime/dart_vm.cc(259)] VM snapshot must be valid. is missing of flutter_assets. For my case, I temporarily get around this matter by doing folowing steps (I use MacOS):

1. run ./gradlew assemble inside .android.
2. go to .android/Flutter/build/outputs/aar/, copy a proper aar file (there're some aar file for debug, release and profile), extract it with unzip command and copy flutter_asssets in extracted folder.
3. create assets folder inside my existing Android project, paste fluter_assets there. Done!

The reason of why flutter doesn't pack flutter_assets to output apk file in my case is still unexplained. It's even more curious when I create a new dummy android project and try to add flutter module to it. It works well. I guess that my real project has some problems in gradle config that causes flutter ignoring flutter_assets

这位大哥的意思就是，我也不知道为什么，module里面的东西就是复制不到android项目里面去，所以我就自己动手了。在项目里面，新建了一个asssets文件夹，然后把aar里面的东西解压后复制过去。我试了下，在debug模式下是可以的，但是在release模式下依然还是很丧啊，那熟悉的crash拂面而来啊。

于是乎我想，既然是gradle的问题，那配下gradle不就完了嘛，奈何知识点不够，那只有继续问google了。幸运的是又一个哥们的一条记录，https://github.com/flutter/flutter/pull/25727，拯救了我，他做了个啥呢，把gralde改了下，现在意思是可以把assets复制过去了，但是现在应该只是在master分支上merge过去了。对于初学者来说，稳不稳定不重要，重要的是让自己的项目能release出去。不然领导问题这个星期干了啥，我说努力让项目跑起来，结果会很残忍的。
flutter channel master，切过去了，然后flutter，开始下载，Building flutter tool...，就这样大概一个晚上过去了。

Failed to retrieve the Dart SDK from: https://storage.googleapis.com/flutter_infra/flutter/9daf5c8d213aeb6c90712dd4b5fb9732b76bf39c/dart-sdk-darwin-x64.zip
If you're located in China, please see this page:
https://flutter.io/community/china
导入这两个镜像，之后的一切都很顺畅
export PUB_HOSTED_URL=https://pub.flutter-io.cn
export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn

下载完，然后再去跑项目，很是期待，然后依然是那张熟悉的脸。想了想是不是我姿势不对，然后就去flutter项目，clean啊，然后gradle assemble，然后失败了。失败了那就对了，这个项目是旧版本flutter新建的啊，所以只好重新新建一个flutter项目。

最后，成功了，VM snapshot must be valid.
Check failed: vm. Must be able to initialize the VM.再见了。