It does crash for me all the time when searching for Tags and then clicking on one of the results. This happens on both, my MacMini and my MacBook Air. All running latest 10.10.1 OS One thing to note, I use a ^ sign in front of every tag so it is easy to display all tags in the search field. E.g. ^invoices ; ^Clients etc. Without those special characters (applies to all special characters) it won't crash. I used it this way on earlier versions without any issue.
I had the same issue but a few restarts later, it's working fine now. It's working as good as it was before under Mavericks. I read somewhere, that for some extensions, you do need to set your Safari preferences to ALWAYS allow cookies. Very happy as this was quite important. If now only Skitch would work .....