The bug
When using the /data merge command without changing a value the command feedback is just "Nothing changed!". It would be better if it contained the context, so for example "The data was not changed".
How to reproduce
Make sure there are other entities in the world
Use the following command
/data merge entity @e[type=!player,limit=1] {}
Linked issues
relates to 1
Comments 3
Yes it is close to a feature request, but similar reports exist which have not been closed and some of them have even been fixed. For example MC-87432.
if I understand right this isn't a bug. this is a suggestion that you can post to this subreddit