internal/lsp: remove useless check
internal/lsp: remove useless check

err must be nil, as the code checks in line 117.

Change-Id: I23d87bdc9489c9ed249bfa1ac61b1ed722121c6a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/217402
Run-TryBot: Peter Weinberger <dd140fb9530d791057dd8833ea6768ff65fcde71@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools