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