エラー内容

git cloneしたものを、MAMPで開発を進めようとし、php artisan serveとコマンドを打つと、以下のエラーが出てしまいました。

【前提】
Composer version 2.0.8
PHP 7.4.9

composer.json
1/Applications/MAMP/htdocs/nuriemon/composer.json
2{
3    "name": "laravel/laravel",
4    "type": "project",
5    "description": "The Laravel Framework.",
6    "keywords": [
7        "framework",
8        "laravel"
9    ],
10    "license": "MIT",
11    "require": {
12        "php": "^7.4",
13        "fideloper/proxy": "^4.2",
14        "fruitcake/laravel-cors": "^1.0",
15        "guzzlehttp/guzzle": "^6.3",
16        "jenssegers/agent": "^2.6",
17        "laravel/framework": "^7.0",
18        "laravel/tinker": "^2.0",
19        "laravel/ui": "^2.0",
20        "nexmo/laravel": "^2.2",
21        "square/square": "6.1.0.20200722",
22        "barryvdh/laravel-snappy": "^0.4.8"
23    },
24    "require-dev": {
25        "barryvdh/laravel-ide-helper": "^2.8",
26        "facade/ignition": "^2.0",
27        "fzaninotto/faker": "^1.9.1",
28        "mockery/mockery": "^1.3.1",
29        "nunomaduro/collision": "^4.1",
30        "phpunit/phpunit": "^8.5"
31    },
32    "config": {
33        "optimize-autoloader": true,
34        "preferred-install": "dist",
35        "sort-packages": true,
36        "secure-http": false
37    },
38    "extra": {
39        "laravel": {
40            "dont-discover": []
41        }
42    },
43    "autoload": {
44        "psr-4": {
45            "App\": "app/"
46        },
47        "classmap": [
48            "database/seeds",
49            "database/factories"
50        ],
51        "files": [
52
53        ]
54    },
55    "autoload-dev": {
56        "psr-4": {
57            "Tests\": "tests/"
58        }
59    },
60    "minimum-stability": "dev",
61    "prefer-stable": true,
62    "scripts": {
63        "post-autoload-dump": [
64            "Illuminate\Foundation\ComposerScripts::postAutoloadDump",
65            "@php artisan package:discover --ansi"
66        ],
67        "post-root-package-install": [
68            "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""
69        ],
70        "post-create-project-cmd": [
71            "@php artisan key:generate --ansi"
72        ]
73    },
74    "repositories": {
75        "packagist": {
76            "type": "composer",
77            "url": "http://packagist.jp"
78        }
79    }
80}
81

#エラー内容

% nuriemon % php artisan serve

In ProviderRepository.php line 208:
                                                     
  Class 'Barryvdh\Snappy\ServiceProvider' not found

クラスがないとのことで、インストールしようとしましたが、以下のエラーが出てしまいました。

% composer require barryvdh/laravel-snappy
Warning: Accessing packagist.jp over http which is an insecure protocol.

                                                   
  [InvalidArgumentException]                       
  Could not find package barryvdh/laravel-snappy.  
                                                   
  Did you mean one of these?                       
      barryvdh/laravel-snappy                      
      jhosep32/laravel-report                      
      jimmyjs/laravel-report-generator             
      coolsam/laravel-report-generator             
      jimmyjs/pdf-report-generators

試したこと

■ １.composer.jsonのsecure-http変更

/Applications/MAMP/htdocs/nuriemon/composer.json

"config": {
    "secure-http": false
}

参考：https://qiita.com/shinkuFencer/items/00c6cdbc0d0e0e081e38

■ ２.dump-autoload

% composer dump-autoload
Generating optimized autoload files
Class App\Http\Resources\AdvertisingResource located in ./app/Http/Resources/Manager/AdvertisingResource.php does not comply with psr-4 autoloading standard. Skipping.
ocramius/package-versions: Generating version class...
ocramius/package-versions: ...done generating version class
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover --ansi

In ProviderRepository.php line 208:
                                                     
  Class 'Barryvdh\Snappy\ServiceProvider' not found  
                                                     

Script @php artisan package:discover --ansi handling the post-autoload-dump event returned with error code 1

参考：https://github.com/barryvdh/laravel-snappy/issues/140

■　３.キャッシュ系

% php artisan config:cache

In ProviderRepository.php line 208:
                                                     
  Class 'Barryvdh\Snappy\ServiceProvider' not found


% php artisan cache:clear

In ProviderRepository.php line 208:

  Class 'Barryvdh\Snappy\ServiceProvider' not found

お力添えいただけると幸いです。