chore:check fs move

Author: luoliwoshang

_cmptest/llcppgend_test.go

@@ -114,7 +114,10 @@ func runDemos(t *testing.T, demosPath string, pkgname, pkgpath, pcPath string) {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(tempDemosPath)
-	os.CopyFS(tempDemosPath, os.DirFS(demosPath))
+	err = os.CopyFS(tempDemosPath, os.DirFS(demosPath))
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	goMod := command(tempDemosPath, "go", "mod", "init", "test")
 	err = goMod.Run()