Being a user of Home Assistant for over 2 year, I managed to create a lot of yaml files. The issue I have is that if an entity changes name (sometimes happens when you are fiddling arround), it can happen that an entity is still in a yaml file but does not exists anymore in HA.
What I would like to see is a check to check if all entities used in the yaml files are verified against HA to see if the entities still exist.
You can do this pretty easily with a code editor/IDE that supports global find and replace.
A find replace is also how I do it right now, but sometimes it happens that an entry is still in a yaml file that does not exist anymore. ie: When you remove an integration that integration might leave entities in automations or scripts. Or (what happens to me sometimes) you make a typo and spend some time restarting HA only to find out that you made a typo