I was trying to build an offline build tool and somehow succeeded in compiling the MIT App Inventor Companion app. But I am having problems while compiling AIA (exported from AI2).
Suggestions and pull requests are welcomed 
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The.aia file generated from exporting a project through the MIT App Inventor user interface does not contain.yail files. The.yail files exist only during the build process as intermediate representations so they are not included in standard project exports. The absence of.yail files in an.aia file export can lead to build failures.
If you clone the MIT App Inventor open source repository and log in there as admin and then create a project and export it, the .aia file will contain the .yail file, but if you log in as a user and then export the .aia file, the .yail file will not be there.
@JEWEL