The most basic information you can supply is what you were trying to do when the game crashed.
"I was starting a mission and the game crashed" is almost impossible to work with.
"I was responding to a sectoid terror mission in a skyranger. It was the first time I deployed a laser rifle" is a lot more useable. The best is a game save (with a LIMITED number of mods, ideally just the FMP, so it is easy to reproduce the issue) a few seconds before the crash.
The best way to debug something is to repeatedly trying to do it, but changing little things. In the example above, if it's the first time you deploy a laser rifle, maybe try without. If that works, the problem is probably with the rifle, etc.
As it is, though, there has just been a HUGE overhaul of how maps work in OpenXCom, making nightlies after a certain date entirely different from earlier ones. Mods designed for the earlier versions (ie all mods) have to be modified to work in the new nightlies (and will then not work in 1.0 and early nightlies).
If your craft spawns in a building and/or UFO, that's a map issue. Similarly, if the FMP tweaked some things for terror missions (or defined new "terror" missions), those probably crash too when starting because required things are missing. There's not really anything to investigate anymore. Someone just needs to get elbow deep in the FMP code and update all the maps stuff (not fun).
Ideally someone could upload an old build from before the changes as a stop gap, until the mods get updated. I use a build from the 27th of october and that seems to have been a sweet spot for nightlies (most features implemented properly but before the map scripts, so works with most stuff). The other thing is for people to fix their mods, but that takes time and effort and I know Solarius is already really busy right now.
