fix: report error when access module_graph in loader (#12639)

* fix: report error when access module_graph in loader

* Apply suggestions from code review

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Copilot <[email protected]>

Author: hardfist

crates/rspack_binding_api/src/module_graph.rs

@@ -28,6 +28,11 @@ impl JsModuleGraph {
 
   fn as_ref(&self) -> napi::Result<(&'static Compilation, &'static ModuleGraph)> {
     let compilation = unsafe { self.compilation.as_ref() };
+    if compilation.build_module_graph_artifact.is_none() {
+      return Err(napi::Error::from_reason(
+        "ModuleGraph is not available during module graph building phase".to_string(),
+      ));
+    }
     let module_graph = compilation.get_module_graph();
 
     Ok((compilation, module_graph))

tests/rspack-test/configCases/loader/access-module-graph/access-mg-loader.js

@@ -0,0 +1,7 @@
+module.exports = function loader(content) {
+  
+  const moduleGraph = this._compilation.moduleGraph;
+  let issuer = moduleGraph.getIssuer(this._module);
+  console.log(issuer);
+  return content;
+}

tests/rspack-test/configCases/loader/access-module-graph/errors.js

@@ -0,0 +1 @@
+module.exports = [/ModuleGraph is not available during module graph building phase/]

tests/rspack-test/configCases/loader/access-module-graph/index.js

@@ -0,0 +1,16 @@
+
+/**
+ * @type {import('@rspack/core').RspackOptions}
+ */
+module.exports = {
+    context: __dirname,
+    entry: './index.js',
+    module: {
+        rules: [
+            {
+                test: /index.js/,
+                use: [{ loader: "./access-mg-loader.js" }]
+            }
+        ]
+    }
+};