Class Laravel\Spark\Providers\SparkServiceProvider not found

While updating some composer dependencies on a Laravel 5.6 using Laravel Spark, I encounter the following error:

@php artisan package:discover

In ProviderRepository.php line 208:
Class 'Laravel\Spark\Providers\SparkServiceProvider' not found  

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

Spark was installed using the Spark Installer (as opposed to composer way).

A quick way to fix the issue is to remove the spark symlink in vendor/laravel.

rm vendor/laravel/spark

Then re-running composer update worked without problem.