🔧 NestJS Dependency Injection: Why Your Services Won't Inject (And How to Fix It Properly)

If you've worked with NestJS for more than a day, you've seen this error:



Error: Nest can't resolve dependencies of the UserService (?).
Please make sure that the argument EmailService at index [1] is available in the UserModule context.






You scratch your head. You added EmailService to the providers array. Why isn't it working? So you...