Virtually all the functionality of this package comes from ruby_language_server.
The first time this fires up (and any time you clear your docker images), the docker image will need to be downloaded - and that may take a few minutes.
Install it, check out a ruby file, and do Outline View: Toggle (alt-o for me). Also View -> Toggle Diagnostics (alt-shift-d)
I'm just trying to get the ball rolling.
Why does this crash?
Do you have docker installed? Is the path /usr/local/bin/docker? You can tweak that in the settings.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.