fix: improve error handling for missing shared modules (#336)

- Add `assertModuleFound` utility to provide clearer error messages when shared modules are not found
- Replace direct `VirtualModule.findModule` calls with `assertModuleFound` in proxy shared module plugin
- Include unit test for new error handling behavior

Author: pcfreak30

src/plugins/pluginProxySharedModule_preBuild.ts

@@ -1,7 +1,6 @@
 import { Plugin, UserConfig } from 'vite';
 import { NormalizedShared } from '../utils/normalizeModuleFederationOptions';
 import { PromiseStore } from '../utils/PromiseStore';
-import VirtualModule from '../utils/VirtualModule';
 import {
   addUsedShares,
   generateLocalSharedImportMap,
@@ -13,6 +12,8 @@ import {
   writePreBuildLibPath,
 } from '../virtualModules';
 import { parsePromise } from './pluginModuleParseEnd';
+import VirtualModule, { assertModuleFound } from '../utils/VirtualModule';
+
 export function proxySharedModule(options: {
   shared?: NormalizedShared;
   include?: string | string[];
@@ -71,18 +72,17 @@ export function proxySharedModule(options: {
               ? {
                   find: new RegExp(`(.*${PREBUILD_TAG}.*)`),
                   replacement: function ($1: string) {
-                    const pkgName = (VirtualModule.findModule(PREBUILD_TAG, $1) as VirtualModule)
-                      .name;
+                    const module = assertModuleFound(PREBUILD_TAG, $1) as VirtualModule;
+                    const pkgName = module.name;
                     return pkgName;
                   },
                 }
               : {
                   find: new RegExp(`(.*${PREBUILD_TAG}.*)`),
                   replacement: '$1',
                   async customResolver(source: string, importer: string) {
-                    const pkgName = (
-                      VirtualModule.findModule(PREBUILD_TAG, source) as VirtualModule
-                    ).name;
+                    const module = assertModuleFound(PREBUILD_TAG, source) as VirtualModule;
+                    const pkgName = module.name;
                     const result = await (this as any)
                       .resolve(pkgName, importer)
                       .then((item: any) => item.id);

src/utils/VirtualModule.ts

@@ -54,6 +54,16 @@ const cacheMap: {
 /**
  * Physically generate files as virtual modules under node_modules/__mf__virtual/*
  */
+export function assertModuleFound(tag: string, str: string = ''): VirtualModule {
+  const module = VirtualModule.findModule(tag, str);
+  if (!module) {
+    throw new Error(
+      `Module Federation shared module '${str}' not found. Please ensure it's installed as a dependency in your package.json.`
+    );
+  }
+  return module;
+}
+
 export default class VirtualModule {
   name: string;
   tag: string;

src/utils/__tests__/VirtualModule.test.ts

@@ -1,4 +1,4 @@
-import { getSuffix } from '../VirtualModule';
+import { getSuffix, assertModuleFound } from '../VirtualModule';
 
 describe('getSuffix', () => {
   it('returns .js for simple package without extension', () => {
@@ -37,3 +37,16 @@ describe('getSuffix', () => {
     expect(getSuffix('@scope.with.dots/pkg/deep/util.spec.ts')).toBe('.ts');
   });
 });
+
+describe('assertModuleFound', () => {
+  it('throws an error when module is not found', () => {
+    const tag = '__test_tag__';
+    const str = 'non-existent-module';
+
+    expect(() => {
+      assertModuleFound(tag, str);
+    }).toThrow(
+      `Module Federation shared module '${str}' not found. Please ensure it's installed as a dependency in your package.json.`
+    );
+  });
+});

src/virtualModules/virtualShared_preBuild.ts

@@ -38,7 +38,7 @@ export function getLoadShareModulePath(pkg: string): string {
 }
 export function writeLoadShareModule(pkg: string, shareItem: ShareItem, command: string) {
   loadShareCacheMap[pkg].writeSync(`
-    
+
     ;() => import(${JSON.stringify(getPreBuildLibImportId(pkg))}).catch(() => {});
     // dev uses dynamic import to separate chunks
     ${command !== 'build' ? `;() => import(${JSON.stringify(pkg)}).catch(() => {});` : ''}