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

Add this in composer.json. Then dusk has to be installed explicitly in your project:

"extra": {
    "laravel": {
        "dont-discover": [
            "laravel/dusk"
        ]
    }
},

I found this solution here

I simply ran composer update and it resolved my issue - Laravel 6.*

In case you're coming from a google search, make sure that you have a .env file in which APP_ENV is set to local. (if you cloned a project from github, the first thing is to run cp .env.example .env. That was actually the problem in my case)

Then run composer install again.