an esoteric bug (and how i fixed it)

shortly after release, i found a bug.

in the 'graph' visualizer, sometimes channel #2 was invisible. 

i was like wtf, what can even cause this. i carefully went through the rendering code but couldn't find anything out of ordinary. then i combed thru the music playing code to see if channel #2 was prone to some state change or something. or variable scopes messing up. 

well, on another run, the channel was visible but not of the color i had set it to. i thought it was weird but i couldn't get an answer. 

and then, after i had gone to bed, it dawned on me. 

the title screen does palette swaps to show the animated rainbow logo. i had forgotten to reset the palette swap for color 10, which just happened to be the color channel #2 was rendered with. 

so when the channel was invisible, the palette swap just happened to land on the background color the last time it was run.