访问 larabbs.test/admin/users 报错，replies config 中方法选项的名称必须是字符串？

全部按照教程走的，但是进入后台larabbs.test/admin/users或者其他admin相关路由，就报错

There are problems with your replies config: The model option must be the string name of a valid Eloquent model (View: /home/Vagrant/code/lbbs/vendor/summerblue/administrator/src/views/layouts/default.blade.php)

config/administrator/replies.php

<?php

use App\Models\Reply;

return [
    'title'   => '回复',
    'single'  => '回复',
    'model'   => Reply::class,

    'columns' => [

        'id' => [
            'title' => 'ID',
        ],
        'content' => [
            'title'    => '内容',
            'sortable' => false,
            'output'   => function ($value, $model) {
                return '<div style="max-width:220px">' . $value . '</div>';
            },
        ],
        'user' => [
            'title'    => '作者',
            'sortable' => false,
            'output'   => function ($value, $model) {
                $avatar = $model->user->avatar;
                $value = empty($avatar) ? 'N/A' : '<img src="'.$avatar.'" style="height:22px;width:22px"> ' . $model->user->name;
                return model_link($value, $model->user);
            },
        ],
        'topic' => [
            'title'    => '话题',
            'sortable' => false,
            'output'   => function ($value, $model) {
                return '<div style="max-width:260px">' . model_admin_link($model->topic->title, $model->topic) . '</div>';
            },
        ],
        'operation' => [
            'title'  => '管理',
            'sortable' => false,
        ],
    ],
    'edit_fields' => [
        'user' => [
            'title'              => '用户',
            'type'               => 'relationship',
            'name_field'         => 'name',
            'autocomplete'       => true,
            'search_fields'      => array("CONCAT(id, ' ', name)"),
            'options_sort_field' => 'id',
        ],
        'topic' => [
            'title'              => '话题',
            'type'               => 'relationship',
            'name_field'         => 'title',
            'autocomplete'       => true,
            'search_fields'      => array("CONCAT(id, ' ', title)"),
            'options_sort_field' => 'id',
            'sortable' => false,
            'output'   => function ($value, $model) {
                return '<div style="max-width:260px">' . model_admin_link(e($model->topic->title), $model->topic) . '</div>';
            },
        ],
        'content' => [
            'title'    => '回复内容',
            'type'     => 'textarea',
        ],
    ],
    'filters' => [
        'user' => [
            'title'              => '用户',
            'type'               => 'relationship',
            'name_field'         => 'name',
            'autocomplete'       => true,
            'search_fields'      => array("CONCAT(id, ' ', name)"),
            'options_sort_field' => 'id',
        ],
        'topic' => [
            'title'              => '话题',
            'type'               => 'relationship',
            'name_field'         => 'title',
            'autocomplete'       => true,
            'search_fields'      => array("CONCAT(id, ' ', title)"),
            'options_sort_field' => 'id',
        ],
        'content' => [
            'title'    => '回复内容',
        ],
    ],
    'rules'   => [
        'content' => 'required'
    ],
    'messages' => [
        'content.required' => '请填写回复内容',
    ],
];

resources/views/layouts/app.blade.php

<!DOCTYPE html>
<html lang="{{ app()->getLocale() }}">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <!-- CSRF Token -->
    <meta name="csrf-token" content="{{ csrf_token() }}">

    <title>@yield('title', 'Neo') - PHP Community</title>
    <meta name="description" content="@yield('description', 'phper community')" />
    <!-- Styles -->
    <link href="{{ asset('css/app.css') }}" rel="stylesheet">
    @yield('styles')
</head>

<body>
    <div id="app" class="{{ route_class() }}-page">

        @include('layouts._header')

        <div class="container">

            @include('layouts._message')

            @yield('content')

        </div>

        @include('layouts._footer')
    </div>
    @if (app()->isLocal())
        @include('sudosu::user-selector')
    @endif
    <!-- Scripts -->
    <script src="{{ asset('js/app.js') }}"></script>
    @yield('scripts')
</body>
</html>

laravel framework