Finding backwards causes unrecoverable error and Abort.

Example. Create a simple writer document with "aaaaa".  Place cursor at end of
letters. Search for a single 'a'. The 4th 'a' is found on the 1st search, the
2nd on the 2nd, the lot on the 3rd and an unrecoverable error on the 4th find.

I expect the 5th then 4th, then 3rd, so something is wrong with the start search
position.

This seams related to realated to reaching the top of the page. It's also a big
problem with backwards searches in tables when the end of the table cell is
reached.