FWIW, a small humber of users have reported that it was because of an alias they created prior to installing 10.2, to relocate some of Logic's content to an external drive, that is responsible for such crashes where Alchemy seems to be the culprit.
Replacing the alias with a Symlink has apparently resolved the issue...
I cannot confirm this myself as i don't have this issue....
Here is one example thread from ACLP
https://discussions.apple.com/thread/7192201