I'm testing the Node.js v7 beta and the stackexchange package fails because devnull errors out. If they publish current master as v0.0.13 or newer, stackexchange should start working again. See observing/devnull#5
However, if you don't want to depend on that happening and if you want to make sure stackexchange continues to work, maybe consider switching logging package or mechanism? Node.js v7 is tentatively scheduled to be released for realz on October 25, I think.