In modules that use the OU search block, typing in a very long word (qqqqqqqqq... and so on for more than 255 characters) caused an error as it tries to insert them into the full-text search index table (blocks_ousearch_words).

I will fix this by restricting words to 255 characters and doing the same on search so that you can also search for them. The number will be a constant so it could potentially be reduced much further in future (but that will require upgrade).