Even though this is an obvious type, execrate is a real word, and it's not the one you are thinking of. It means "to express great loathing".
An obvious typo, you might even say!
When correcting someone on a finer point, it’s only fair to subject yourself to the same even-handed criticism before posting.
(I am a descriptivist, not a prescriptivist when it comes to spelling and grammar, but I am a stickler for the rules when it’s time to follow them! It’s fair to assume that we didn’t know there was going to be a test, and I have made typos also. I just thought this was ironic. Carry on!)