Here are three options.
Just make the edit.
Better: make the edit, and leave a comment thanking the other user for drawing your attention to the problem.
Best (in my opinion): make the edit, and also edit into your question a word of thanks to the user for pointing out the problem. This way the user can delete the comment, and no one gets confused about ...
The problem with this is many-fold:
What if the new tags no longer fit the content after text edit ?
What if wrong tags give the wrong impression of which version of the problem is wanted to be solved ?
What happens if it looks like only a text edit is ongoing, but they then change or add tags ?
How can we easily ensure mutual exclusion, without adding to ...