This is what I get when I try to start a new server in the logs with the current build of DF:
NullReferenceException: Object reference not set to an instance of an object
at BiomePrefabExclusion.Patches_PrefabManager.GetPrefabWithDistrict+<>c.<Transpiler>b__0_1 (System.Collections.Generic.List`1[T] list, WorldGenerationEngineFinal.Township ts) [0x0001a] in <745f5265f5b9461295f83a7664c0c313>:0
at (wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition.<Transpiler>b__0_1(System.Collections.Generic.List`1<PrefabData>,WorldGenerationEngineFinal.Township)
at (wrapper dynamic-method) WorldGenerationEngineFinal.PrefabManager.DMD<WorldGenerationEngineFinal.PrefabManager::GetPrefabWithDistrict>(WorldGenerationEngineFinal.District,POITags,int,Vector2i,Vector2i,bool,Vector2i,WorldGenerationEngineFinal.Township,single)
at WorldGenerationEngineFinal.StreetTile.SpawnMarkerPartsAndPrefabs (PrefabData _parentPrefab, Vector3i _parentPosition, System.Int32 _parentRotations, System.Int32 _depth, System.Single totalDensityLeft) [0x002e9] in <2fd3859bfeea484e99f6b20bc94f186d>:0
at WorldGenerationEngineFinal.StreetTile.spawnStreetTile (Vector2i tileMinPositionWorld, System.Boolean isHighwayTile, System.String streetPrefabName, System.Single totalDensityPointsLeft, System.Int32 baseRotations) [0x00160] in <2fd3859bfeea484e99f6b20bc94f186d>:0
at WorldGenerationEngineFinal.StreetTile.SpawnPrefabs () [0x0008b] in <2fd3859bfeea484e99f6b20bc94f186d>:0
at WorldGenerationEngineFinal.Township.SpawnPrefabs () [0x00041] in <2fd3859bfeea484e99f6b20bc94f186d>:0
at WorldGenerationEngineFinal.TownPlanner+<SpawnPrefabs>d__2.MoveNext () [0x00085] in <2fd3859bfeea484e99f6b20bc94f186d>:0
at UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) [0x00026] in <799d47ea3fd1460380efad1aacedaf7c>:0