Catch php warning when host is not complete

[shyim]

In Request.php line 128:
                                         
  [ErrorException]                       
  Warning: Undefined array key "scheme"  
                                         

Exception trace:
  at /Users/shyim/Code/sw6/vendor/async-aws/core/src/Request.php:128

I used as endpoint just localhost:9000, this triggers a warning because the scheme is missing. Maybe scheme should be required or has an fallback to something 🤔