It is strange I have both mods and without problems, it has to be someone else that derives the error, I put a list of the mods that I have and that I have zero problems:
Spoiler
"Adjusted Sector",
"sd_advancedHullMods",
"ApproLight",
"ApproLightPlus",
"archeus",
"aria",
"raccoonarms",
"automatic-orders",
"lw_autosave",
"Battlestar Galactica Revived",
"timid_admins",
"blackrock_driveyards",
"Celestial Mount Circle",
"CombatAnalytics",
"timid_commissioned_hull_mods",
"COPS",
"lw_console",
"diyplanets",
"istl_dam",
"diableavionics",
"edshipyard",
"fluffships",
"Aic",
"sun_fuel_siphoning",
"gates_awakened",
"gflportraitpack",
"hvbplussimple",
"hiigaran_resurgence",
"sun_hyperdrive",
"hyperionsystems",
"IndEvo",
"Imperium",
"kiith-nabaal-shipyard",
"LTA",
"lw_lazylib",
"MagicLib",
"missingships",
"more_hullmods",
"playermoreflag",
"Neutrino",
"nexerelin",
"ORA",
"wyv_planetaryShieldAccessControl",
"Polaris_Prime",
"PulseIndustry",
"tahlan_scalartech",
"SCY",
"swp",
"bonomel_skilledup",
"solsystem",
"sw",
"timid_supply_forging",
"Terraforming and Station Construction",
"Templars",
"underworld",
"US",
"URW",
"va11portraits",
"vayrasector",
"lw_version_checker",
"shaderLib"
I will review it as soon as I can and see what causes it, but I have never had that error, it may be another mod that you have that interferes with the creation of the faction in the game, to avoid those errors automatically I recommend you put the nexerelin and create a random nucleus, it is probably that two factions try to spawn on the same system when generating the galaxy and in that topic I have not touched anything just change the name of the faction so that it was only Hiigara without the descendants that makes no sense I'll check it and see if there's something wrong