Merge pull request webpack#7445 from webpack/bugfix/no-id

rewrite module reference correctly after replacing ConcatenatedModule

Author: sokra

lib/optimize/ModuleConcatenationPlugin.js

@@ -286,7 +286,13 @@ class ModuleConcatenationPlugin {
 							}
 							compilation.modules.push(newModule);
 							for (const reason of newModule.reasons) {
-								reason.dependency.module = newModule;
+								if (reason.dependency.module === concatConfiguration.rootModule)
+									reason.dependency.module = newModule;
+								if (
+									reason.dependency.redirectedModule ===
+									concatConfiguration.rootModule
+								)
+									reason.dependency.redirectedModule = newModule;
 							}
 							// TODO: remove when LTS node version contains fixed v8 version
 							// @see https://github.com/webpack/webpack/pull/6613

test/cases/optimize/side-effects-scope-hoisting/index.js

@@ -0,0 +1,8 @@
+import { a } from "pmodule";
+
+it("should not crash with null id", function() {
+	expect(a).toBe("a");
+});
+
+if(Math === undefined)
+	console.log(module); // prevent scope hoisting of this module