laravel Class ‘Form’ not found の対処法

調べてみると、composer.jsonでlaravelcollective/htmlを追記してcomposer updateするって書いてあるけど、やってみるとエラーでうまくインストールできなかったので以下をやってみたらすんなりFormファサードを読み込めた

・composer.jsonは編集せずそのまま
・ターミナルから composer require laravelcollective/html ←version指定しない
...これだけ。
すると、composerが自動でlaravelのバージョンに合わせたlaravelcollectiveをインストールしてくれる

$ composer require laravelcollective/html #version指定しない
Using version ^6.1 for laravelcollective/html
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
  - Installing laravelcollective/html (v6.1.2): Downloading (100%)
Package jakub-onderka/php-console-color is abandoned, you should avoid using it. Use php-parallel-lint/php-console-color instead.
Package jakub-onderka/php-console-highlighter is abandoned, you should avoid using it. Use php-parallel-lint/php-console-highlighter instead.
Package phpunit/php-token-stream is abandoned, you should avoid using it. No replacement was suggested.
Writing lock file
Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover --ansi
Discovered Package: facade/ignition
Discovered Package: fideloper/proxy
Discovered Package: laravel/tinker
Discovered Package: laravelcollective/html
Discovered Package: nesbot/carbon
Discovered Package: nunomaduro/collision
Package manifest generated successfully.