Color selection in Shogun crashes sfrotz

If you try to use the COLOR command in Shogun to change the foreground/background colours, sfrotz will crash with a "Print at illegal address" error.

This appears to be because it's getting the colours from the interpreter, and when you change colours it tries to print the current colour an entry from this table based on its index.

<CONSTANT COLOR-TABLE
	  <TABLE ;0 "no change"
		 ;1 "the default color"
		 ;2 "black"
		 ;3 "red"
		 ;4 "green"
		 ;5 "yellow"
		 ;6 "blue"
		 ;7 "magenta"
		 ;8 "cyan"
		 ;9 "white"
		 ;10 "light gray"
		 ;11 "gray"
		 ;12 "dark gray">>

But apparently sf_GetColourIndex() will return a colour index that's outside of this table as the default background, I think. (Judging by screenshots on MobyGames, the default background colour should be some shade of grey, but sfrotz uses some kind of blue instead).