I am also seeing this trying to run Android app:
error: Error: Unable to resolve module @joplin/fork-uslug from /home/roman/dev/joplin/packages/renderer/MdToHtml.js: @joplin/fork-uslug could not be found within the project or in these directories:
../renderer/node_modules
../../node_modules
/home/roman/dev/joplin/packages/app-mobile/node_modules/@joplin/fork-uslug