If "adjust by value" would hit 0, do nothing, instead of setting speed to 0.07

[KuroZantetsuken]

I thought having two buttons that adjust the speed by +1 and -1 (or even +/-0.5, you get it) respectively would be a neat setup, but it's too easy to press -1 too many times and get stuck with a .07 at the end of the speed. I think it would make sense if an input change like that made no sense, it would do nothing instead of something unexpected like that.