os: remove useless error check

Change-Id: Ifeb5fecc6e28b79ac03e7dc2ce9531fe5eed3097
GitHub-Last-Rev: 087cf95965920c96befad5adb9e481bdf913d50a
GitHub-Pull-Request: golang/go#66260
Reviewed-on: https://go-review.googlesource.com/c/go/+/570895
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sean Liao <sean@liao.dev>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Florian Lehner <lehner.florian86@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>

src/os/os_windows_test.go

@@ -64,9 +64,6 @@ func TestSameWindowsFile(t *testing.T) {
 	}
 
 	p := filepath.VolumeName(path) + filepath.Base(path)
-	if err != nil {
-		t.Fatal(err)
-	}
 	ia3, err := os.Stat(p)
 	if err != nil {
 		t.Fatal(err)