Laravel 5.7: UrlGenerator TypeError running php artisan dusk or phpunit

I'm getting this error when I run either php artisan dusk or phpunit:

TypeError: Argument 2 passed to Illuminate\Routing\UrlGenerator::__construct(
must be an instance of Illuminate\Http\Request, null given,
called in RoutingServiceProvider.php

A lot of suggestions for fixing this say to remove any instances of asset( or url( from config files. I'm not using either of those in any config file.

php artisan and php artisan route:list run fine.

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