i get this every 10 mins in console 

NullReferenceException: Object reference not set to an instance of an object
Invalid Position: scientist_corpse[945258] (-4000.1, 7.1, 244.4) (destroying)
Invalid Position: item_drop_backpack[945270] (-4000.1, 7.1, 244.4) (destroying)
7713171[905690/7713171] died (Generic)
NullReferenceException: Object reference not set to an instance of an object
Invalid Position: scientist_corpse[945274] (-4000.4, 10.0, 250.6) (destroying)
Invalid Position: item_drop_backpack[945280] (-4000.4, 9.9, 250.6) (destroying)
2275547[905766/2275547] died (Generic)
NullReferenceException: Object reference not set to an instance of an object
8471913[905735/8471913] died (Generic)
NullReferenceException: Object reference not set to an instance of an object
Invalid Position: scientist_corpse[945284] (-4000.4, 19.2, 247.0) (destroying)
Invalid Position: scientist_corpse[945292] (-4000.3, 28.1, 243.8) (destroying)
6550443[905721/6550443] died (Generic)
NullReferenceException: Object reference not set to an instance of an object
Invalid Position: item_drop_backpack[945300] (-4000.4, 19.1, 247.0) (destroying)
Invalid Position: item_drop_backpack[945302] (-4000.3, 28.0, 243.8) (destroying)
1259180[905749/1259180] died (Generic)
NullReferenceException: Object reference not set to an instance of an object
Invalid Position: scientist_corpse[945306] (-4000.4, 28.2, 265.1) (destroying)
Invalid Position: scientist_corpse[945315] (-4000.3, 25.3, 257.2) (destroying)
Invalid Position: item_drop_backpack[945320] (-4000.4, 28.1, 265.1) (destroying)
Invalid Position: item_drop_backpack[945322] (-4000.9, 25.3, 257.2) (destroying)
Invalid Position: rhib[905589] (-4000.1, 9.2, 255.0) (destroying)​

Invalid position is OK. About null reference exception, please open log that you specified in start file via -logfile, since this error isn't complete (full), but it is in the log file. P.S. logfile should be a full path in start script

hello i cant believe, that u get this every 10min ^^ or u spawn every 10min a CargoShip or the CH47. or some plugin try spawn a cargoship every 10min and it destroys it outside from map.

for me this error happend, if a CargoShip or CH47 is leaving the map and there are some NPC left. and this is the full nre

NullReferenceException: Object reference not set to an instance of an object
  at HTNPlayer.OnKilled (HitInfo info) [0x00021] in <396141fde09c4c65a45b8addaf757edb>:0 
  at BaseCombatEntity.Die (HitInfo info) [0x00066] in <396141fde09c4c65a45b8addaf757edb>:0 
  at BasePlayer.Die (HitInfo info) [0x0009f] in <396141fde09c4c65a45b8addaf757edb>:0 
  at BasePlayer.OnInvalidPosition () [0x00009] in <396141fde09c4c65a45b8addaf757edb>:0 
  at BaseEntity.TransformChanged () [0x0003b] in <396141fde09c4c65a45b8addaf757edb>:0 
  at BaseEntity.NetworkPositionTick () [0x0001f] in <396141fde09c4c65a45b8addaf757edb>:0 
  at InvokeHandler.DoTick () [0x000d6] in <3813eca1819e4fc283426c24f1e2afcc>:0 
  at InvokeHandler.LateUpdate () [0x0000c] in <3813eca1819e4fc283426c24f1e2afcc>:0 ​

i never spawn a cargo ship 
I will try to get the full log