Apparently, when you set the borders of the sprite to the whole sprite (i.e. left, right, top and bottom borders all overlap at the same point), Unity throws an out-of-memory exception, lags, then crashes, continuously. This didn’t happen in the previous beta versions I used (15-18). While I doubt I should be using borders like that, I don’t think it’s reasonable to assume the editor will crash until I force it to unload that sprite asset.
Is this happening during sprite editing or when using it for a UI element.
Not during the sprite editing, and I was using it as a UI element, so I suppose that would be when it happened.
I would submit a bug with a repo project if you can.