It erroneously claims that your max value isn't greater than your min.

With everything else as the default I adjusted HUE_SHADES to 72 for each normal, glowing and transparent. The game started fine.

I changed the range to 0.0 -> 1.0 for hues, and still no crash. It might be easier to reproduce if you just pastebin the config that produces a crash.

Maybe try setting the exponent to 1?
I believe this is the exact settings I was using when it was crashing:
flatcoloredblocks.cfg.txt

Should be fixed in v6.8