Why I am getting Individual declarations in merged declaration 'RegisterComponent' must be all exported or all local.ts(2395)?

I have this code:

import { RegisterComponent } from './register.component';
import { Component, OnInit } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
import { Router } from '@angular/router';
import { AuthService } from '../../../../src/app/services/auth.service';
import { User } from '../../../Models/User';

@Component({
  selector: 'app-register',
  templateUrl: './register.component',

})
export class RegisterComponent implements OnInit {
  repeatpass: string = 'none';

  constructor(private authService: AuthService,
    private router: Router) { }

  ngOnInit(): void {
  }

  goToMenu() {
    this.router.navigate(['componenets/food-menu']);
  }

  registerForm = new FormGroup({
    firstname: new FormControl("",[Validators.required,Validators.minLength(2), Validators.pattern("[a-zA-Z].*")]),
    lastname: new FormControl("",[Validators.required,Validators.minLength(2), Validators.pattern("[a-zA-Z].*")]),
    email: new FormControl("", [Validators.required,Validators.email]),
    mobile: new FormControl("", [Validators.required,Validators.pattern("[0-9]*"),Validators.minLength(10),Validators.maxLength(10),]),
    gender: new FormControl("", [Validators.required]),
    pwd: new FormControl("", [Validators.required,Validators.minLength(6),Validators.maxLength(15)]),
    rpwd: new FormControl(""),
  });

  registerSubmited() {
    {
    this.repeatpass = 'none'
    let modal: User = {} as User;
    this.authService.registerUser(modal);
  }
}
  get FirstName(): FormControl {
    return this.registerForm.get("firstname") as FormControl;
  }
  get LastName(): FormControl {
    return this.registerForm.get("lastname") as FormControl;
  }
  get Email(): FormControl {
    return this.registerForm.get("email") as FormControl;
  }
  get Mobile(): FormControl {
    return this.registerForm.get("mobile") as FormControl;
  }
  get Gender(): FormControl {
    return this.registerForm.get("gender") as FormControl;
  }
  get PWD(): FormControl {
    return this.registerForm.get("pwd") as FormControl;
  }

}

I am getting Individual declarations in merged declaration 'RegisterComponent' must be all exported or all local.ts(2395) ?