So, this bug is pretty much: the program completely fails to include the content of the pdf files. The pages seem to be there, as well as some graphics, but there is ZERO text.
I've attached the two source files, and the output file.
Command used was stapler sel GameAIPro-ch1.pdf GameAIPro-ch2.pdf output.pdf
GameAIPro-ch1.pdf
GameAIPro-ch2.pdf
output.pdf