Champ Select Mastery Bug

I got a message saying,

"Error An unexpected error has occurred Sorry about that. We've sent a report to the server"

while in champ select. This message came up after I made an adjustment to a mastery page and it asked me if I would like to save the changes. This is a video taken out of champ select but this is exactly what had happened. (https://gyazo.com/1b6e0b91c95809407d08233bf29c31ca)

I thought it might have changed my mastery page to the one I currently had on but realized that the last one I used was bond of stone and I was put in game with deathfire touch. This is weird because I do not have a mastery page with death fire touch. (This is not me trolling but you can check my account. I have not changed any of the mastery pages for a few hours.)