internal/lsp: swallow hover error over identifier not found

Fixes https://github.com/golang/go/issues/32967

Change-Id: I41245582f95f8a31e0d1990eac7aeb2a9c29cf05
GitHub-Last-Rev: 5d257b66138be4b9ea502af89ff48f0574c91718
GitHub-Pull-Request: golang/tools#140
Reviewed-on: https://go-review.googlesource.com/c/tools/+/186997
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
diff --git a/internal/lsp/hover.go b/internal/lsp/hover.go
index 5f0be11..78f6937 100644
--- a/internal/lsp/hover.go
+++ b/internal/lsp/hover.go
@@ -28,7 +28,7 @@
 	}
 	ident, err := source.Identifier(ctx, view, f, identRange.Start)
 	if err != nil {
-		return nil, err
+		return nil, nil
 	}
 	hover, err := ident.Hover(ctx, s.preferredContentFormat == protocol.Markdown, s.hoverKind)
 	if err != nil {