Forticlient on Linux Javascript error

I'm on Debian, forticlient version 7.0.0.0018 amd64. When I try to start the application I get this error: https://imgur.com/fRoZrQW.png

I have restarted my computer and it made an empty white window appear but nothing appeared. Closing and opening it after that gave the javascript error.

 

For others googling:

Uncaught Exception: TypeError [ERR_INVALID_CALLBACK]: Callback must be a function at maybeCallback (fs.js:129:9) at Object.writeFile (fs.js:1137:14) [...]