NPM: After "npm link" module is not found

The problem was that the main property of package.json was pointing to a non-existing file. It seems that the problem can happen due to multiple reasons so be sure to take a look at other answers.

I ran into this issue because of NVM, I was running one version of node for the dependency and another for the dependant.

Deleting package-lock.json then running npm install again resolved the issue for me.