Laravel form validation error

Hi everybody.
I'm learning Laravel and I've got an issue with the Auth code. The issue is that Laravel seems to pretend that to register a new user all registration form fields be filled, even the not required ones.

This is my RegisterController.php

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use App\Providers\RouteServiceProvider;
use App\User;
use Illuminate\Foundation\Auth\RegistersUsers;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;
use Illuminate\Http\Request;
use Illuminate\Auth\Events\Registered;

class RegisterController extends Controller
{
  /*
  |--------------------------------------------------------------------------
  | Register Controller
  |--------------------------------------------------------------------------
  |
  | This controller handles the registration of new users as well as their
  | validation and creation. By default this controller uses a trait to
  | provide this functionality without requiring any additional code.
  |
  */

  use RegistersUsers;

  /**
   * Where to redirect users after registration.
   *
   * @var string
   */
  protected $redirectTo = RouteServiceProvider::HOME;

  /**
   * Create a new controller instance.
   *
   * @return void
   */
  public function __construct()
  {
    $this->middleware('guest');
  }

  /**
   * Get a validator for an incoming registration request.
   *
   * @param  array  $data
   * @return \Illuminate\Contracts\Validation\Validator
   */
  protected function validator(array $data)
  {
    return Validator::make($data, [
      'name' => ['required', 'string', 'max:255'],
      'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
      'password' => ['required', 'string', 'min:8', 'confirmed'],
      'company' => ['string'],
      'website' => ['string'],
      'phone' => ['numeric'],
      'mobile' => ['numeric'],
      'type' => ['string'],
    ]);
  }

  /**
   * Create a new user instance after a valid registration.
   *
   * @param  array  $data
   * @return \App\User
   */
  protected function create(array $data)
  {
    return User::create([
      'name' => $data['name'],
      'email' => $data['email'],
      'password' => Hash::make($data['password']),
     //using data_get doesn't change anything
      'company' => data_get( $data, 'company'),
      'website' => data_get($data, 'website'),
      'phone' => data_get($data, 'phone'),
      'mobile' => data_get($data, 'mobile'),
    	'type' => data_get($data, 'type'),
      // 'company' => $data['company'],
      // 'website' => $data['website'],
      // 'phone' => $data['phone'],
      // 'mobile' => $data['mobile'],
    	// 'type' => $data['type'],
    ]);
  }

  /**
   * https://laraveldaily.com/auth-after-registration-redirect-to-previous-intended-page/
   * Handle a registration request for the application.
   *
   * @param  \Illuminate\Http\Request  $request
   * @return \Illuminate\Http\Response
   */
  public function register(Request $request)
  {
    $this->validator($request->all())->validate();

    event(new Registered($user = $this->create($request->all())));

    $this->guard()->login($user);

    return $this->registered($request, $user)
      ?: redirect()->intended($this->redirectPath());
  }

}

I originally followed a tutorial. Later I wanted to add some field to user table and I used this migration:

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class AddPersonalDataToUserTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('users', function (Blueprint $table) {
            $table->string('company')->nullable();
            $table->string('website')->nullable();            
            $table->string('phone')->nullable();            
            $table->string('mobile')->nullable();            
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('users', function (Blueprint $table) {
            $table->dropColumn(['company',  'website', 'phone', 'mobile']);
        });
    }
}

I thought that leaving added columns empty whould have worked fine but I've got validation errors like "The website must be a string", so I googled a bit and I have created a new migration:

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class AddDefaultNullToSomeColumn extends Migration
{
	/**
	 * Run the migrations.
	 *
	 * @return void
	 */
	public function up()
	{
		Schema::table('users', function (Blueprint $table) {
			$table->string('company')->nullable()->default(null)->change();
			$table->string('website')->nullable()->default(null)->change();
			$table->string('phone')->nullable()->default(null)->change();
			$table->string('mobile')->nullable()->default(null)->change();
		});
	}

	/**
	 * Reverse the migrations.
	 *
	 * @return void
	 */
	public function down()
	{
		Schema::table('users', function (Blueprint $table) {
			$table->string('company')->nullable()->change();
			$table->string('website')->nullable()->change();
			$table->string('phone')->nullable()->change();
			$table->string('mobile')->nullable()->change();
		});
	}
}

and finally, here there is my registration form

@extends('master')
@section('title', __('auth.registerTitle') )

@section('content')
<div class="hero-wrap hero-wrap-2" style="background-image: url('/images/bg_2b.jpg');" data-stellar-background-ratio="0.5">
  <div class="overlay"></div>
  <div class="container">
    <div class="row no-gutters slider-text align-items-center justify-content-center">
      <div class="col-md-8 ftco-animate text-center text-center mt-5">
        <p class="breadcrumbs mb-0"><span class="mr-3"><a href="/">{{ __('menu.home') }} <i class="ion-ios-arrow-forward"></i></a></span> <span>{{ __('auth.menu-register') }}</span></p>
        <h1 class="mb-3 bread">{{ __('auth.menu-register') }}</h1>
      </div>
    </div>
  </div>
</div>

<section class="ftco-section ftco-partner">
  <div class="container">
    <div class="row block-9 justify-content-center mb-5">
      <div class="col-md-10 mb-md-5">

        <h2 class="float-left">{{ __('auth.registerTitle') }}</h2>
        <form method="post">
          @foreach ($errors->all() as $error)
            <p class="alert alert-danger">{{ $error }}</p>
          @endforeach

          {{ csrf_field() }}
          <div class="form-group">
          <label for="name" class="col-lg-12 control-label">{{ __('auth.name') }}</label>
            <div class="col-lg-12">
              <input type="text" class="form-control" id="name" placeholder="{{ __('auth.name') }}" name="name" value="{{ old('name') }}">
            </div>
          </div>

          <div class="form-group">
            <label for="email" class="col-lg-12 control-label">{{ __('auth.email') }}</label>
            <div class="col-lg-12">
              <input type="email" class="form-control" id="email" placeholder="{{ __('auth.email') }}" name="email" value="{{ old('email') }}">
            </div>
          </div>

          <div class="form-group">
            <label for="password" class="col-lg-12 control-label">{{ __('auth.pwd') }}</label>
            <div class="col-lg-12">
              <input type="password" class="form-control"  name="password">
            </div>
          </div>

          <div class="form-group">
            <label for="password" class="col-lg-12 control-label">{{ __('auth.pwdrepeat') }}</label>
            <div class="col-lg-12">
              <input type="password" class="form-control"  name="password_confirmation">
            </div>
          </div>

          <div class="form-group">
            <label for="company" class="col-lg-12 control-label">{{ __('auth.company') }}</label>
            <div class="col-lg-12">
              <input type="text" class="form-control" id="company" placeholder="{{ __('auth.company') }}" name="company" value="{{ old('company') }}">
            </div>
          </div>

          <div class="form-group">
            <label for="website" class="col-lg-12 control-label">{{ __('auth.website') }}</label>
            <div class="col-lg-12">
              <input type="text" class="form-control" id="website" placeholder="{{ __('auth.website') }}" name="website" value="{{ old('website') }}">
            </div>
          </div>

          <div class="form-group">
            <label for="phone" class="col-lg-12 control-label">{{ __('auth.phone') }}</label>
            <div class="col-lg-12">
              <input type="text" class="form-control" id="website" placeholder="{{ __('auth.phone') }}" name="phone" value="{{ old('phone') }}">
            </div>
          </div>

          <div class="form-group">
            <label for="mobile" class="col-lg-12 control-label">{{ __('auth.mobile') }}</label>
            <div class="col-lg-12">
              <input type="text" class="form-control" id="mobile" placeholder="{{ __('auth.mobile') }}" name="mobile" value="{{ old('mobile') }}">
            </div>
          </div>

          {{-- <div class="form-group">
            <label for="type" class="col-lg-12 control-label">{{ __('auth.type') }}</label>
            <div class="col-lg-12">
                <select class="form-control" name="type" id="type">
                    <option value="admin">Admin</option>
                    <option value="super_admin">Super Admin</option>
                    <option value="member">Member</option></select>
            </div>
          </div> --}}

          <div class="form-group">
            <div class="col-lg-10 col-lg-offset-2">
							<input type="hidden" name="type" id="type" value="member" />
              <button type="reset" class="btn btn-default">{{ __('auth.cancel') }}</button>
              <button type="submit" class="btn btn-primary">{{ __('auth.submit') }}</button>
            </div>
          </div>
        </form>
      </div>
    </div>
  </div>
</section>
@endsection

Actually, the db table allows those fields to be NULL and their default value is NULL but I still get those errors and to successfully register a new user I must fill all fields in the form.
What I am missing here?