callgraph/vta: Removes dead return statement (misc cleanup).

Change-Id: Ie95810f8118eb8602b89b753d1567d8f50aaefd7
Reviewed-on: https://go-review.googlesource.com/c/tools/+/403356
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Tim King <taking@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Tim King <taking@google.com>
diff --git a/go/callgraph/vta/graph.go b/go/callgraph/vta/graph.go
index 37308f8..365d7a5 100644
--- a/go/callgraph/vta/graph.go
+++ b/go/callgraph/vta/graph.go
@@ -681,7 +681,6 @@
 	default:
 		panic(fmt.Errorf("unsupported value %v in node creation", val))
 	}
-	return nil
 }
 
 // representative returns a unique representative for node `n`. Since