This is referring to a numerical range in one of the files, Unfortunately, the "gs" doesn't have anything to do with the problem itself. The value should always be positive, but this means the current value is negative.
I know we've dealt with the issue before, but I can't think of where it was to save me life at the moment. I feel like it was definitely in one of the ship entity files, but I'm afraid I can't come up with any more specifics. Something about switiching two values... I'll think on it and let you know if I come up with anything.