Fix connection error not being returned resulting in errors like `gopls: remote disconnected: <nil>`.
Change-Id: I67fa1143b2fa0fd44c946040fc1bad51b1636183
GitHub-Last-Rev: 9ebae5c3b85b7bb73eb67bb1ee8028f6f504a83d
GitHub-Pull-Request: golang/tools#334
Reviewed-on: https://go-review.googlesource.com/c/tools/+/339709
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Peter Weinberger <pjw@google.com>