Failing build from source


I’m playing around with building an Electron app from source, as I’d like to combine it into my build process, however following the bash commands in the GitHub docs is throwing up an error in ninja when running

$ export GYP_DEFINES="project_name=myapp product_name=MyApp"
$ python script/
$ python script/
$ python script/ -c Release -t myapp
ninja: Entering directory 'out/R'
ninja: error: '/Users/david/electron-repo/electron/vendor/brightray/vendor/download/libchromiumcontent/static_library/natives_blob.bin', needed by 'MyApp' Framework.framework/Versions/A/Resources/natives_blob.bin', missing and no known rule to make it

Has anyone got any idea why it’s not working and whether it’s something I can fix myself (and how)?