KingPin

While this fixes the continuous string of NRE's, it still generates several when destroying a craft that goes on rails. This also causes the "unable to revert" bug. New output log for 2.1.0 with the same craft file as before: https://www.dropbox.com/s/f70keueoulg3ova/KSP%20Testing%202.1.0.rar

It indeed seems to happen when something that has produced smoke particles goes on-rails and gets removed by the game. I tried a few simple tests with the Dev 12 version, version 2.0.1, as well as the version that HotRockets comes with, and they all generate the same NPE spam. Here's a log file and small example craft, hope it's of any use. https://www.dropbox.com/s/ewa04f10bfz0pve/KSP%20Testing.rar

Oh man, you really know when to update. I had just downloaded and installed 1.5.3 and now 1.6.0 is available.