I'm getting this. I am not sure if it's being triggered by placing a lock. I just placed a lock on a horse and I didn't see the error come up.

Failed to call hook 'CanDeployItem' on plugin 'VehicleDeployedLocks v1.12.0' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.VehicleDeployedLocks+VehicleInfoManager.GetVehicleInfo (BaseEntity entity) [0x00000] in <c4033d44998e4841bffce6a0683ac1db>:0
at Oxide.Plugins.VehicleDeployedLocks.GetVehicleAndInfo (BaseEntity entity, BasePlayer basePlayer, BaseEntity& vehicle) [0x0009c] in <c4033d44998e4841bffce6a0683ac1db>:0
at Oxide.Plugins.VehicleDeployedLocks.CanDeployItem (BasePlayer basePlayer, Deployer deployer, NetworkableId entityId) [0x00078] in <c4033d44998e4841bffce6a0683ac1db>:0
at Oxide.Plugins.VehicleDeployedLocks.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00bc5] in <c4033d44998e4841bffce6a0683ac1db>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <87ce9ac9776a48658bc55eae6debe38b>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <88ec380b221d4997a7d40107fc469ad4>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <88ec380b221d4997a7d40107fc469ad4>:0

This may be due to the pre-release version I gave you. I'll make sure NREs are not possible when I release it publicly.