Handle exeptions from feature provider

[lgeiger]

Feature providers may throw exceptions which are currently unhandled which may result in a language server crash.

E.g.:

• yapf may throw a parsing error Forever formatting loop atom-community/ide-python#44 (comment)
• jedi may throw a "maximum recursion depth" error on hover

I suggest we wrap the calls to external feature providers in try/catch statements and return a ResponseError if they fail instead of leaving the exception unhandled.

What do you think?

[gatesn]

Huh, it's weird that exceptions aren't caught by this line: https://github.com/pavlov99/json-rpc/blob/master/jsonrpc/manager.py#L115

As invoked by https://github.com/palantir/python-language-server/blob/develop/pyls/server.py#L49

[lgeiger]

Thanks for the links. I'll investigate

[ferozco]

Think this was resolved with #261