Failed to call hook 'cmd_UI_PAY_TAXI'

Failed to call hook 'cmd_UI_PAY_TAXI' on plugin 'CopterTaxi v1.3.4' (InvalidCastException: Specified cast is not valid.)

at System.Convert.ToInt32 (System.Object value) [0x00003] in <41d29b352f6a475ab1bf7c6628b82790>:0

at Oxide.Plugins.CopterTaxi.cmd_UI_PAY_TAXI (ConsoleSystem+Arg arg) [0x00011] in <d7d59e00a6ff41ea92320bdd78a437ca>:0

at Oxide.Plugins.CopterTaxi.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00f4f] in <d7d59e00a6ff41ea92320bdd78a437ca>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <15f61ddda771464d8246ebdce8ff4811>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <15f61ddda771464d8246ebdce8ff4811>:0

updated

Tried completely deleting the old file, as well as the json file and reloaded. Still getting errors when using /taxi

Failed to call hook 'cmd_CallTaxi' on plugin 'CopterTaxi v1.3.5' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.CopterTaxi.CreateImage (Oxide.Game.Rust.Cui.CuiElementContainer& container, System.String name, System.String panel, System.String color, System.String image, System.String aMin, System.String aMax, System.Single Fadeout, System.Single Fadein, System.UInt64 skin) [0x0002a] in <494df12df1e74c36b02411089fae9d55>:0 
  at Oxide.Plugins.CopterTaxi.CreateCallCopterTaxiUI (BasePlayer player) [0x00215] in <494df12df1e74c36b02411089fae9d55>:0 
  at Oxide.Plugins.CopterTaxi.cmd_CallTaxi (BasePlayer player, System.String c, System.String[] a) [0x00036] in <494df12df1e74c36b02411089fae9d55>:0 
  at Oxide.Plugins.CopterTaxi.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00e25] in <494df12df1e74c36b02411089fae9d55>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <15f61ddda771464d8246ebdce8ff4811>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <15f61ddda771464d8246ebdce8ff4811>:0