A proof of concept for the misbehavior of the ShouldBeUnique mechanism with the missing model.
Issue: laravel/framework#49890
Pull request with the fix: laravel/framework#50211
Execute the following:
git clone https://github.com/naquad/laravel-bug-report-49890.git
cd laravel-bug-report-49890
cp .env.example .env
./artisan migrate
./artisan app:poc