It used to paste what it could, indicating that "some cell states were reduced" when I had Golly 2.4. Now I am running Golly 2.6, windows 64-bit, and rather tired of losing unsaved work to this issue.
EDIT: It occurs to me that I might have been running 2.4 when I encountered this issue. My shortcuts are unlabeled
EDIT2: In attempts to replicate, I found that it was a 2.4 thing. I opened a pattern from the clipboard in Life using ctrl-shift-O, then tried to paste in a different pattern in LifeHistory with V, and Golly would crash. It only crashed when the initial pattern was opened using ctrl-shift-O, not after patterns drawn in or pasted in, which is how I used to do things, explaining why I remember it not being a problem in the past.
However, this doesn't crash Golly in 2.6. I'll just go ahead and delete 2.4 from my computer so I don't make the mistake again.