[4.x] Handle redis connection exception on DumpWatcher register

[aidanthewiz]

Fixes issue #620

When trying to composer install locally with the redis cache driver configured, if redis is unreachable the following error occurs:

php_network_getaddresses: getaddrinfo for redis failed: nodename nor servname provided, or not known

  at [internal]:0
      1▕ 

      +24 vendor frames 
  25  [internal]:0
      Illuminate\Foundation\Application::Illuminate\Foundation\{closure}(Object(Laravel\Telescope\TelescopeServiceProvider))

      +5 vendor frames 
  31  artisan:35
      Illuminate\Foundation\Console\Kernel::handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
Script @php artisan package:discover --ansi handling the post-autoload-dump event returned with error code 1

This PR fixes the issue by handling the occurred exception and returning from the WatchDumper registration handler. Same for the Telescope::startRecording method.