NestJS - Injected service is undefined in the constructor

The "emitDecoratorMetadata": true is missing in your tsconfig.json file.

Just stumbled across the same issue in one of my providers - the problem was that I forgot to annotate the provider with an @Injectable() decorator after I have added it to the respective module.

One of my providers was scoped with REQUEST scope. I removed it and it resolved more errors than one.