Comment out CustomModule stub for testing

Author: cursoragent

tests/fixtures/go/main.go

@@ -132,6 +132,6 @@ func main() {
 }
 
 // Stub CustomModule for test parsing purposes
-var CustomModule struct{}
+// var CustomModule struct{}
 
-func (CustomModule) track(userId string, eventName string, params map[string]any) {}
+// func (CustomModule) track(userId string, eventName string, params map[string]any) {}