`npm install` doesn't install all the dependencies

[trasa]

Symptoms: you run npm install, it creates the node_modules directory and puts some dependencies in there but doesn't put them all, so you get errors when you run about failing to load modules / modules not found.

Two things to try:

1. delete the node_modules directory and try running npm install and see if it works the 2nd time
2. (more desperate) If that doesn't work, try deleting the package-lock.json and node_modules directories and re-install. (This might cause more problems, though.)