I was powering a repeater with a redstone torch, which then connected to a vertical stack of glow with redstone on it (standard vertical wiring using glowstone). When I removed the torch, the repeater remained power, even though it was receiving no power, and so did the redstone on all the blocks of glowstone. When I tried to remove these glitched blocks, my server crashed. The sandstone block indicates where the torch was placed and removed. Attached is a screenshot of my setup after the crash and the crash report itself.