scout:import about laravel-scout-elasticsearch

[matchish]

The error throws because of \ElasticSearch\Client isn't registered in a service provider

The package uses \ElasticSearch\Client from official package, but does not try to configure it, so feel free do it in your app service provider. But if you don't want to do it right now, you can use Matchish\ElasticSearchServiceProvider from the package.
Register the provider, adding to config/app.php

'providers' => [
    // Other Service Providers

    \Matchish\ScoutElasticSearch\ElasticSearchServiceProvider::class
],