Laravel 5验证随机跳过

First time I encounter this issue, When validating a form:

Sometimes it just skips the validation and erases all the fields

When i enter an incorrect emailaddress and keep pressing submit eventually it will reset all the fields at random.. Without giving the "invalid email" error.

These are my rules.

public function rules()
{
    return [
        'voornaam' => 'required',
        'achternaam' => 'required',
        'email' => 'required|email',
        'afhalen' => 'required',
        'telefoon' => 'numeric'
    ];
}

Any idea's? Thanks!