Nest can't resolve dependencies of the UserService (?). Please make sure that the argument at index [0] is available in the current context

Having some problems, di/circular-references I'm sure I'm doing wrong, I just can't see it.

Any help would be much appreciated

user.module.ts

import { Module } from '@nestjs/common';
import { UserService } from './user.service';
import { UserController } from './user.controller';
import { PrismaService } from 'src/prisma/prisma.service';

@Module({
  controllers: [UserController],
  providers: [UserService, PrismaService],
})
export class UserModule {}

user.service.ts

import { Injectable } from '@nestjs/common';
import type { PrismaService } from 'src/prisma/prisma.service';
import type { CreateUserDto } from './dto/create-user.dto';
import { hash } from 'argon2';

@Injectable()
export class UserService {
  constructor(private readonly prisma: PrismaService) {}

  async create(createUserDto: CreateUserDto) {
    const { password, ...user } = createUserDto;
    const hashedPassword = await hash(password);
    return await this.prisma.users.create({
      data: {
        password: hashedPassword,
        ...user,
      },
    });
  }

  async findByEmail(email: string) {
    this.prisma.users.findUnique({
      where: {
        email,
      },
    });
  }
}

auth.module.ts

import { Module } from '@nestjs/common';
import { AuthService } from './auth.service';
import { AuthController } from './auth.controller';
import { UserService } from 'src/user/user.service';
import { PrismaService } from 'src/prisma/prisma.service';

@Module({
  controllers: [AuthController],
  providers: [AuthService, UserService, PrismaService],
})
export class AuthModule {}

auth.service.ts

import {
      ConflictException,
      forwardRef,
      Inject,
      Injectable,
    } from '@nestjs/common';
    import type { CreateUserDto } from 'src/user/dto/create-user.dto';
    import { UserService } from 'src/user/user.service';
    
    @Injectable()
    export class AuthService {
      constructor(
        @Inject(forwardRef(() => UserService))
        private readonly userService: UserService,
      ) {}
    
      registerUser(createUserDto: CreateUserDto) {
        const user = this.userService.findByEmail(createUserDto.email);
        if (user) throw new ConflictException('User already exists!');
        return this.userService.create(createUserDto);
      }
    }

app.module.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { PrismaService } from './prisma/prisma.service';
import { AuthModule } from './auth/auth.module';
import { UserModule } from './user/user.module';

@Module({
  imports: [AuthModule, UserModule],
  controllers: [AppController],
  providers: [AppService, PrismaService],
})
export class AppModule {}

ERROR [ExceptionHandler] Nest can't resolve dependencies of the UserService (?). Please make sure that the argument Function at index [0] is available in the AuthModule context.

Potential solutions:
- Is AuthModule a valid NestJS module?
- If Function is a provider, is it part of the current AuthModule?
- If Function is exported from a separate @Module, is that module imported within AuthModule?
  @Module({
    imports: [ /* the Module containing Function */ ]
  })

Error: Nest can't resolve dependencies of the UserService (?). Please make sure that the argument Function at index [0] is available in the AuthModule context.

Potential solutions:
- Is AuthModule a valid NestJS module?
- If Function is a provider, is it part of the current AuthModule?
- If Function is exported from a separate @Module, is that module imported within AuthModule?
  @Module({
    imports: [ /* the Module containing Function */ ]
  })

Was originally having "Nest can't resolve dependencies of the UserService. I then deleted the UserModule entirely and just used the AuthModule, everything worked. Can you tell me where I am wrong. Thanks in advance.

There is a circular dependency.

constructor(@Inject(forwardRef(() => UserService)) private readonly userService: UserService) {}

add this line in your service of auth. (Auth.service.ts)

and try to share the code of AuthServices too.

also export the services from your every module.

@Module({
controllers: [UserController],
providers: [UserService, PrismaService],
exports:[UserService]
})
export class UserModule {}

do same for other modules too