only getting supply drops no vehicles

Hi im having an issue with the plugin only giving supply drops instead of the vehicles? 

console report: 

| Exception while calling NextTick callback (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.DropVehicles+<CheckSignalDrop>c__AnonStorey1.<>m__0 () [0x00012] in <d05e65a6311541f7886c52b6fedb2eee>:0

at Oxide.Core.OxideMod.OnFrame (System.Single delta) [0x00051] in <9882f28dc2204b4dba514a9ad18f5042>:0

(20:46:18) | Exception while calling NextTick callback (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.DropVehicles+<CheckSignalDrop>c__AnonStorey1.<>m__0 () [0x00012] in <d05e65a6311541f7886c52b6fedb2eee>:0

at Oxide.Core.OxideMod.OnFrame (System.Single delta) [0x00051] in <9882f28dc2204b4dba514a9ad18f5042>:0

(20:46:25) | Exception while calling NextTick callback (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.DropVehicles+<CheckSignalDrop>c__AnonStorey1.<>m__0 () [0x00012] in <d05e65a6311541f7886c52b6fedb2eee>:0

at Oxide.Core.OxideMod.OnFrame (System.Single delta) [0x00051] in <9882f28dc2204b4dba514a9ad18f5042>:0

Addressed in DM

Changed Status from Pending to Closed

Changed Fixed In to 1.5.9