PHPStorm中的类显示红线

Question

文件名有一条红色波浪线，但我没有看到在我创建的类中弹出错误。这是PHPStorm的错误吗？没有迹象表明我错过了什么。并且悬停在红线上并不会显示更多信息。

<?php

namespace App\Classes;

use App\Events\EventGenerator;
use Illuminate\Database\Eloquent\Model;
use App\Classes\User;

class User extends Model {

    use EventGenerator;

    // Define Table Setup with fillabe fields
    protected $table = 'users';
    protected $fillable = ['name', 'user_reference', 'first_name', 'last_name', 'user_type_id', 'created_at', 'updated_at'];
    public $timestamps = true;

    // Set class properties
    public function set($data) {
        foreach ($data as $key => $value) {
            $this->{$key} = $value;
        }
        return $this;
    }

    public function getAllUsers() {
        $responders = User::all();
        return $responders;
    }


    public function getUser($userReference) {
        $user = User::where('user_reference', '=', $userReference)->first();
        return $user;
    }
}