Electron-log doesn't not in production app

I don’t know how happened
electron-log is in package.json dependencies

but I use electron-packager to compile to Mac App

Error: Cannot find module ‘electron-log’

I open app/Contents/Resources/app/node_modules/electron-log

well… it’s empty in this folder.

Is it a bug or
how can I fix it?

and this is my build command:
electron-packager . TCUCourse --out=out --overwrite --platform=darwin --arch=x64 --icon=icon/apple.icns --prune=true --squirrel-install --ignore=node_modules/electron-* --electron-version=6.0.7 --version-string.CompanyName=Jerry --version-string.ProductName=TCUCourse