Using /fill kicks all players

So I was on my 20w48a testing server today and then performed the /fill command and ran the command like this "/fill ~ 0 ~ ~ 255 ~ air" and then all players were kicked out, and we were kicked from IndexOutOfBoundsException.

How to reproduce?

1. Create a 20w48a Server
2. Connect to the server using "localhost"
3. Type "/fill ~ 0 ~ ~ 255 ~ air"
4. And you are disconnected from the server

Exception should be listed in the attachments.