When you place a glowstone block next to a piston and acitvate the piston (e.g. with a lever), the glowstone normaly moves like the most blocks do, but if you use the debug stick on the piston with an right click (to make it on) while it is off and than you activate and after that turn off the piston, the glowstone suddenly breaks. On the screenshot, if you put the lever twice, the glowstone will break!

Note: I think it happens because the debug stick makes it so that the piston is at the exact same position as the glowstone. When you activate the piston, it updates and because 2 blocks can't be at the same position, the glowstone breaks