Laravel mix - Cant run npm run watch

I'm trying to make something in VueJS and in order to check the changes I have to run npm run watch to see the result but I can't do that and it is giving me an error message.

> @ watch /home/vagrant/code/stage
> cross-env NODE_ENV=development node_modules/webpack/bin/webpack.js --watch --progress --hide-modules --config=node_modules/laravel- 
mix/setup/webpack.config.js

sh: 1: cross-env: not found
npm ERR! file sh
npm ERR! code ELIFECYCLE
npm ERR! errno ENOENT
npm ERR! syscall spawn
npm ERR! @ watch: `cross-env NODE_ENV=development 
node_modules/webpack/bin/webpack.js --watch --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config
npm ERR! spawn ENOENT
npm ERR!
npm ERR! Failed at the @ watch script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/vagrant/.npm/_logs/2018-04-04T09_20_31_009Z-debug.log

In my package.json is says that laravel-mix isn't even installed. I tried updating it and installing it again but nothing works. Updating and installing give me a load of warnings and errors as well. What is causing this?

via Chebli Mohamed