Can't add items to the list returned by ship:dockingports [BUG]

[nuggreat]

When you get the list SHIP:DOCKINGPORTS you can't add items to that list as you get a "specified cast is not valid" error.
Code to reproduce:

SET dl TO SHIP:DOCKINGPORTS.
dl:ADD(0).

There is also an assoceated entry in the KSP log from the C# side of the mod

[LOG 15:29:23.789] System.InvalidCastException: Specified cast is not valid.
  at (wrapper castclass) System.Object.__castclass_with_cache(object,intptr,intptr)
  at kOS.Safe.Encapsulation.Suffixes.OneArgsSuffix`1[TParam].Call (System.Object[] args) [0x00000] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Encapsulation.Suffixes.DelegateSuffixResult.Invoke (kOS.Safe.Execution.ICpu cpu) [0x00226] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Compilation.OpcodeCall.StaticExecute (kOS.Safe.Execution.ICpu cpu, System.Boolean direct, System.Object destination, System.Boolean calledFromKOSDelegateCall) [0x002b2] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Compilation.OpcodeCall.Execute (kOS.Safe.Execution.ICpu cpu) [0x0000d] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Execution.CPU.ExecuteInstruction (kOS.Safe.Execution.ProgramContext context, System.Boolean doProfiling) [0x00203] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Execution.CPU.ContinueExecution (System.Boolean doProfiling) [0x00040] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 
  at kOS.Safe.Execution.CPU.KOSFixedUpdate (System.Double deltaTime) [0x000b0] in <44fd6c0ba1d84aeaa0b357d09ee83648>:0 

which combined with the lack of verbosity makes me thing this is a C# problem getting back into kerboScript some what similar to issue #3006

There is a simple work around where one simply creates a new list of there own and populates it with everything from the dockingports list but that should not be necessary.