The road drone apparently died - saw this around the same time

 [DronePatrol] Drone NONE died

 

Then when issuing rd via console or /rd this hook fail is shown and no drone is spawned

 Failed to call hook 'CmdSpawnRoadDrone' on plugin 'DronePatrol v1.0.14' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.DronePatrol.CmdSpawnRoadDrone (Oxide.Core.Libraries.Covalence.IPlayer iplayer, System.String command, System.String[] args) [0x002c8] in <e0e247af2ac34f668c4f899ae0169983>:0 
  at Oxide.Plugins.DronePatrol.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0097f] in <e0e247af2ac34f668c4f899ae0169983>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <3606d2af539c45e4b5c61658e6a8b307>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0

 

Edited March 24 by undertow

Also for when the the monument drone dies

Failed to call hook 'CmdSpawnMonumentDrone' on plugin 'DronePatrol v1.0.14' (KeyNotFoundException: The given key was not present in the dictionary.)
  at System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) [0x0001e] in <eae584ce26bc40229c1b1aa476bfa589>:0 
  at Oxide.Plugins.DronePatrol.CmdSpawnMonumentDrone (Oxide.Core.Libraries.Covalence.IPlayer iplayer, System.String command, System.String[] args) [0x000b1] in <e0e247af2ac34f668c4f899ae0169983>:0 
  at Oxide.Plugins.DronePatrol.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0092b] in <e0e247af2ac34f668c4f899ae0169983>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <3606d2af539c45e4b5c61658e6a8b307>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0

 

Edited March 24 by undertow