I have over 104 addons so if you have a way to list your addons, then I could fairly easily see what you have that is different from me. Maybe I can help narrow it down. No promises though. However yes, searching for "item equip error type" in all the Lua files in your addons folder would tell you easily. There are no automatic tools to do that though.
Code:
dir /A:D /B > list.txt
If you open a command prompt and navigate to your Addons folder and type that it will make a txt file of the folders which would be as close to an addon list as you will get.
If the windows search is not searching the lua files, you can use e.g. the free tool Notepad++.
I already shared that info a few times now with you Marazota, afai can remember. Maybe write it down now
Notepad++ -> Menu "search" -> Search in files
Select your addons folder an enter the text you want to search.
In 90% of the cases you'll find the text or parts of it really quick and are able to contact the author of that addon then.