Bunch of different System.NullReferenceException crashes.

Have over 300 hours in game, not one single crash. Suddenly today get dozens of different NullReferenceException crashes, that appear to have different causes. Tried a new seed, went about 10 cycles, crashed again. Verified game files. Here is the most recent crash log:

System.NullReferenceException: Object reference not set to an instance of an object
  at PathGrid.GetCost (System.Int32 cell) <0x259661f2f30 + 0x00010> in <3d436e4ec1d5455793674ec559b0cc77>:0
  at PathProber.GetCost (System.Int32 cell) [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Navigator.GetNavigationCost (System.Int32 cell) [0x00008] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Navigator.GetNavigationCost (System.Int32 cell, CellOffset[] offsets) [0x00018] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Workable.GetNavigationCost (Navigator navigator, System.Int32 cell) [0x00009] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at FetchManager+FetchablesByPrefabId.GatherReachablePickups (Navigator navigator) [0x00055] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at FetchManager+FetchablesByPrefabId.UpdatePickups (PathProber path_prober, Navigator worker_navigator, UnityEngine.GameObject worker_go) [0x00007] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at FetchManager+UpdatePickupWorkItem.Run (System.Object shared_data) [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at WorkItemCollection`2[WorkItemType,SharedDataType].InternalDoWorkItem (System.Int32 work_item_idx) [0x0000d] in <3ca21dc18eae422d87255277091f8593>:0
  at JobManager.DoNextWorkItem () [0x0001a] in <3ca21dc18eae422d87255277091f8593>:0
  at JobManager+WorkerThread.Run () [0x0001e] in <3ca21dc18eae422d87255277091f8593>:0

  at UnityEngine.Debug.LogError (System.Object message) [0x00000] in <72b60a3dd8cd4f12a155b761a1af9144>:0
  at Debug.LogError (System.Object obj) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at JobManager+WorkerThread.PrintExceptions () [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at JobManager.Run (IWorkItemCollection work_items) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at GlobalJobManager.Run (IWorkItemCollection work_items) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at FetchManager.UpdatePickups (PathProber path_prober, Worker worker) [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at PickupableSensor.Update () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Sensors.UpdateSensors () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Sensors.OnBrainPreUpdate () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at Brain.UpdateBrain () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at MinionBrain.UpdateBrain () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at BrainScheduler+BrainGroup.RenderEveryTick (System.Single dt, System.Boolean isAsyncPathProbeEnabled) [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at BrainScheduler.RenderEveryTick (System.Single dt) [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
  at SimAndRenderScheduler+RenderEveryTickUpdater.Update (IRenderEveryTick updater, System.Single dt) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at UpdateBucketWithUpdater`1[DataType].Update (System.Single dt) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at StateMachineUpdater+BucketGroup.AdvanceOneSubTick (System.Single dt) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at StateMachineUpdater.RenderEveryTick (System.Single dt) [0x00000] in <3ca21dc18eae422d87255277091f8593>:0
  at Game.LateUpdate () [0x00000] in <3d436e4ec1d5455793674ec559b0cc77>:0
Build: U51-600112-S

 

DxDiag.txt Antigravity Pit Cycle 13.sav