FIX: Request textDocument/hover failed

[piktur]

Great news from #81! Looking forward to the improvement. In the meantime this PR attempts to ensure correct type for String addition:

VSCode log output

[Error] Request textDocument/definition failed.
  Message: [TypeError] no implicit conversion of nil into String
  Code: -32603 

and backtrace from VSCode DevTools

Cheers

[castwide]

Thanks for tracking this one down. It'll be included in version 0.25.1.

[castwide]

Writing a spec for this case, I noticed that similar problems can happen with a few other Fragment methods, so I added some more changes to ensure that word, remainder, signature, base, and chain (and methods that compose from them like whole_word) always return strings. Thanks again for the catch.

[piktur]

Brilliant, thanks again for your work.