I am graduating soon and in the last minute my advisor found an issue in one major theorem in my thesis. In an hour, my advisor sent me a write up with a fix. The result is a little bit different than what I have, but it does the job.
I was not expecting him to fix this issue. We were supposed to meet and discuss this issue. Instead, my advisor just sent an email with this fix. Since this is the major result in my thesis and my advisor's contribution is more significant than mine, what is the appropriate way to acknowledge this in my thesis?