Strange Exception telling the file does not exist or is not readable in Laravel 5.1

I'm getting reports with exceptions like these:

exception 'InvalidArgumentException' with message 'The file "/var/www/http://ift.tt/1MWBYvF" does not exist or is not readable.' in /var/www/http://ift.tt/1RdcwHL
Stack trace:
#0 /var/www/http://san
...

As you can see it's weird that it's trying to access that does not exist for sure /var/www/http://sandbox4b5ace....

The type of Exception may change. I've put here the full dump of it.

I've no clue of why is this throwing this Exception, the only thing I recognize is the file path has as string taken from the mailgun api sandbox credentials. So, I'ts strange.

Any light on this is welcome.

The full project is here

via Chebli Mohamed