IndexError in signature.py on textDocument/signatureHelp #459
Description
I'm using pyls via coc.nvim, and when it attempts to grab the signature of a class method, it's throwing an IndexError on this line:
It looks like in this case s.docstring() is somehow not returning a string, which causes splitlines() to not return an array, and [0] causes the error.
This was easy to mitigate by just catching that error and returning returning .splitlines() without the index, but I wanted to flag it here in case your team might have a better idea for why/when that wouldn't return an array, and what the right way to mitigate it is.
