jantimon/reproduction-webpack-import-module-bug

Reproduction of a webpack importModule loader bug

Reproduction:

npm i
node server.mjs

Reproduction for Next.js

Error:

Reason:

./loader.cjs uses the Webpack loader API this.importModule which invokes vm.runInThisContext to execute the module code.

However, as soon as the package.json file includes "type": "module" vm.runInThisContext does not have access to require and module anymore.

Possible fix:

Add require and module to compilation.hooks.executeModule.tap(PLUGIN_NAME, (options, context) => { ... }):

diff --git a/node_modules/webpack/lib/javascript/JavascriptModulesPlugin.js b/node_modules/webpack/lib/javascript/JavascriptModulesPlugin.js
index 4249a2f..31cd251 100644
--- a/node_modules/webpack/lib/javascript/JavascriptModulesPlugin.js
+++ b/node_modules/webpack/lib/javascript/JavascriptModulesPlugin.js
@@ -441,8 +441,11 @@ class JavascriptModulesPlugin {
 					const { module, moduleObject } = options;
 					const code = source.source();
 
+					const {createRequire} = require("module");
+					const universalRequire = typeof createRequire === "function" ? createRequire(module.resource) : require;
+
 					const fn = vm.runInThisContext(
-						`(function(${module.moduleArgument}, ${module.exportsArgument}, ${RuntimeGlobals.require}) {\n${code}\n/**/})`,
+						`(function(${module.moduleArgument}, ${module.exportsArgument}, ${RuntimeGlobals.require}, require, module) {\n${code}\n/**/})`,
 						{
 							filename: module.identifier(),
 							lineOffset: -1
@@ -453,7 +456,9 @@ class JavascriptModulesPlugin {
 							moduleObject.exports,
 							moduleObject,
 							moduleObject.exports,
-							context.__webpack_require__
+							context.__webpack_require__,
+							universalRequire,
+							moduleObject
 						);
 					} catch (e) {
 						e.stack += printGeneratedCodeForStack(