title: Custom fields in laravel 5.6 default auth causing error
body: <p>Before posting this question i've already referred to <a href="https://stackoverflow.com/questions/49935424/how-to-add-custom-field-in-default-registration-form-of-laravel-5-6">How to add custom field in default registration form of Laravel 5.6?</a></p>
  
  <p>But no solution for my problem. I wanted to add custom fields in my laravel 5.6 fresh install with it's default make:auth.</p>
  
  <p>this is my migration for creating user table</p>
  
  <p><a href="https://i.stack.imgur.com/oZzn2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oZzn2.png" alt="enter image description here"></a></p>
  
  <p>this is my registercontrller for auth and i've implemented my custom fields here</p>
  
  <p><a href="https://i.stack.imgur.com/dGWfs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dGWfs.png" alt="enter image description here"></a></p>
  
  <p>and here is fillable array of my model user.php which extends authenticble </p>
  
  <p><a href="https://i.stack.imgur.com/VanQd.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VanQd.png" alt="enter image description here"></a></p>
  
  <p>This is dd() response from register controller </p>
  
  <p><a href="https://i.stack.imgur.com/IepjW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IepjW.png" alt="enter image description here"></a></p>
  
  <p>And in the end here is the error that i'm getting after doing all this.</p>
  
  <p><a href="https://i.stack.imgur.com/mgXBS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mgXBS.png" alt="enter image description here"></a></p>
  
  <p>Any help will be appreciated . 
  Thanks in advance. </p>