While reviewing syslog to look for realpath problems I noticed these, in case anyone cares:
GUPnPAV-1.0: vfprintf %s NULL in "URL: %s, ID: %s." desktoptojson: vfprintf %s NULL in "Warning: %s (%s:%u, %s) " mono: vfprintf %s NULL in "%s %2d %02d:%02d:%02d%.*s %d%s" valac: vfprintf %s NULL in " value="%s"" xpcshell: vfprintf %s NULL in "%s: Resetting desktop app info dirs from %s to %s" gst-plugin-scanner: vfprintf %s NULL in "%s%s" (The last one was quite special because it was followed by "last message repeated 44329 times", though looking at older logs that seems unusual).