At the command "/ gamerule", a non-existent game rules have been modified. And, it is false indications.
I think that it should be displayed this way
"This game rule does not exist." And, you should be displayed.
Happened bug:
When you execute, "the game rules [non-existent game Rule name was updated to [quantity]. And, are displayed.
Steps to Reproduce:
・ Implanting "/ gamerule [non-existent game rules] [quantity]" in the chat field
It is intended that you can create gamerules.