They also could have just changed it into a float to accomodate the 0.1x and thereby didnt think of making it unsigned.I'll make a completely unfounded hypothesis and assume catch rate is an unsigned number, so it cannot fall under 0.
I'm curious, though, as since the Beast Ball has a 0.1x multiplier on non-Ultra Beasts, how does it work on Pokemon with a Catch Rate below 10?
Say, is it actually possible to catch a Beldum with one?