Report a bug not working and a Graves bug

I was going to report a bug I found on the PBE but when I open the report a bug, I get this error:

{"message":"Cannot read property 'toString' of null","error":{}}

The bug was Graves dying. Once he died, his body was reloading in the ground. The enemy team was Trundle,Jinx,Zac,Blitzcrank and Olaf. Our team was Bard, Lucian, Rumble Graves and Me as Kindred.I tried to screenshot but since I have dual monitor, it screenshot my other monitor