I ran into an issue caused by the recent mod split. Basically, if you try to start a new Nexerelin campaign with one of the colonial competitor factions/fleets (Warhawk Republic, Ashen Keepers, etc.), then you will crash to desktop.
The source of the problem is that the blueprints for all the colonial competitor factions are still defined in the Kadur Remnant mod's special_items.csv file. So, when Nexerelin tries to give you the freebie blueprint to start your campaign, it can't find it unless you also have the Kadur Remnant mod enabled.
Anyway, it should be a fairly straightforward fix if I'm understanding the problem correctly (i.e. just move the colonial competitor blueprint entries from the Kadur Remnant mod to a new special_items.csv file for this mod). Until then, the simplest workaround is to just keep both mods enabled (or just don't try to start a game with one of the colonial competitor faction fleets)...