Angular 5执行ng build --prod时出现编译内部错误求助

Hey there, let's work through this frustrating build error together. That unknown identifier undefined message from the Angular compiler almost always ties back to misconfigurations in your dependency injection setup or module declarations. Here are targeted steps to track down and fix the issue:

• Audit your NgModule providers
  Dig into every @NgModule in your project, especially the providers array. Look for:

  • Entries referencing a service or token that wasn’t imported (e.g., providers: [MyService] but no import { MyService } from './my.service').
  • Providers using useValue or useFactory that point to an undefined value (like { provide: APP_CONFIG, useValue: undefined }).
  • Typos in service or token names (a small typo can make the compiler look for an undefined identifier).

• Check lazy-loaded module dependencies
  If you’re using lazy loading, ensure all tokens and services referenced in lazy modules are properly imported or provided. It’s easy to accidentally reference a root-only token in a lazy module without importing it first.

• Hunt for circular dependencies
  Circular loops between services can trigger this obscure compiler error. Run ng build --prod --verbose to get more detailed logs—this often points to the specific service pair causing the loop. You can refactor the services to break the cycle (e.g., using Injector to lazy-load one of the dependencies).

• Update Angular core packages
  Outdated versions of @angular/compiler or core Angular libraries sometimes have bugs that cause this issue. Update to the latest stable version with these commands:

  npm install @angular/cli@latest @angular/core@latest @angular/compiler@latest --save
  npm install
  

• Clean build artifacts and cache
  Stale cache or corrupted node modules can lead to weird compiler glitches. Wipe them clean and rebuild:

  ng clean
  rm -rf node_modules package-lock.json
  npm install
  ng build --prod
  

• Test without AOT (for debugging)
  Temporarily run ng build --prod --aot=false to see if the error disappears. If it does, the problem is definitely in code that AOT compilation is stricter about—circle back to your provider and module configurations to find the issue.

内容的提问来源于stack exchange，提问作者Alexandr