lsp jump to def works poorly if file contains errors

[cjhopman]

For this code:

def bad():

def foo():
  some_ref()

You can't jump-to-def on some_ref(). We do have a red squiggle for the bad function, so that's good. Maybe we should jump to the error.

For this:

def foo():
  some_ref()

def bad() -> UndefinedType.type:
  pass

You can't jump-to-def on some_ref(). We also don't identify the error with a red squiggle.