Ruby class navigation stopped working. Can't run classes or specs via context menu.

In the last week or so I've suddently lost the ability to navigate to classes via Command+Click. I also can't right-click and run a spec.

The logs seem to have lots of errors (attached). I tried turning off a bunch of plugins (I recently added some for Coffee Script, Angular and Node).

I've tried:
- restart
- invaidate caches and restart
- delete project and start again from sources

I also started having trouble finding my specified SDK and gemset. I resorted to deleting the .ruby-version and .ruby-gemset from my project directory to get around this.

Dan