[Proposal] Using mustRun to force exception 
[Proposal] Using mustRun to force exception 

I had a permission error that was hidden from me till I did `mustRun`.
The hidden error was `sh: 1: /home/vagrant/Code/sponsor/vendor/laravel/cashier/src/Laravel/Cashier/bin/linux-x86_64/phantomjs: Permission denied`

Now it will throw in error. Prior to this the PDF printed but could not be opened.
jurihub/cashier,laravel/cashier,beeseenmedia/cashier,DougSisk/laravel-cashier,5outh/cashier,kyranb/cashier,rained23/cashier,rained23/cashier,readybytes/cashier,phroggyy/cashier,ryross/cashier,readybytes/cashier,kyranb/cashier,ryross/cashier,mpociot/cashier,laravel/cashier,phroggyy/cashier,beeseenmedia/cashier,jurihub/cashier,mpociot/cashier,5outh/cashier,ryross/cashier,DougSisk/laravel-cashier