Setting a writeable suffix of an active ManeuverNode causes NullReferenceException

[MaxRebo1]

In KSP v1.2.1, using kOS version 1.0.2-pre-2, setting a settable suffix of aManeuverNodethat has been added to the flight plan causes aNullReferenceException.

Example code demonstrating this behavior - mvrtest.ks:

SET nd TO NODE(TIME:SECONDS+300,1,1,1).
ADD nd.
SET nd:ETA TO 600.

Exemplary log excerpt:

[LOG 13:05:05.592] kOS: At 1:/mvrtest, line 3
SET nd:ETA TO 600.
                       ^
[LOG 13:05:05.594] System.NullReferenceException: Object reference not set to an instance of an object
  at ManeuverNode.OnGizmoUpdated (Vector3d dV, Double ut) [0x00000] in <filename unknown>:0 
  at kOS.Suffixed.Node.ToNodeRef () [0x00000] in <filename unknown>:0 
  at kOS.Suffixed.Node.<InitializeSuffixes>b__12_1 (kOS.Safe.Encapsulation.ScalarValue value) [0x00000] in <filename unknown>:0 
  at kOS.Safe.Encapsulation.Suffixes.SetSuffix`1[kOS.Safe.Encapsulation.ScalarValue].Set (System.Object value) [0x00000] in <filename unknown>:0 
  at kOS.Safe.Encapsulation.Structure.ProcessSetSuffix (IDictionary`2 suffixes, System.String suffixName, System.Object value) [0x00000] in <filename unknown>:0 
  at kOS.Safe.Encapsulation.Structure.SetSuffix (System.String suffixName, System.Object value) [0x00000] in <filename unknown>:0 
  at kOS.Safe.Compilation.OpcodeSetMember.Execute (ICpu cpu) [0x00000] in <filename unknown>:0 
  at kOS.Safe.Execution.CPU.ExecuteInstruction (IProgramContext context, Boolean doProfiling) [0x00000] in <filename unknown>:0 
[LOG 13:05:05.599] Code Fragment
File                 Line:Col IP   label   opcode operand
====                 ====:=== ==== ================================  
                        0:0   0000         jump +27 
[built-in]              0:0   0001 @LR00   pushscope -999 0 
[built-in]              0:0   0002 @LR01   push $runonce 
[built-in]              0:0   0003 @LR02   swap 
[built-in]              0:0   0004 @LR03   storelocal 
[built-in]              0:0   0005 @LR04   push $filename 
[built-in]              0:0   0006 @LR05   swap 
[built-in]              0:0   0007 @LR06   storelocal 
[built-in]              0:0   0008 @LR07   push _KOSArgMarker_ 
[built-in]              0:0   0009 @LR08   push $filename 
[built-in]              0:0   0010 @LR09   eval 
[built-in]              0:0   0011 @LR10   push True 
[built-in]              0:0   0012 @LR11   push null 
[built-in]              0:0   0013 @LR12   call load() 
[built-in]              0:0   0014 @LR13   br.false +6 
[built-in]              0:0   0015 @LR14   push $runonce 
[built-in]              0:0   0016 @LR15   br.false +4 
[built-in]              0:0   0017 @LR16   pop 
[built-in]              0:0   0018 @LR17   push 0 
[built-in]              0:0   0019 @LR18   return 1 deep 
[built-in]              0:0   0020 @LR19   push $entrypoint 
[built-in]              0:0   0021 @LR20   swap 
[built-in]              0:0   0022 @LR21   storelocal 
[built-in]              0:0   0023 @LR22   call $entrypoint 
[built-in]              0:0   0024 @LR23   pop 
[built-in]              0:0   0025 @LR24   push 0 
[built-in]              0:0   0026 @LR25   return 1 deep 
1:/mvrtest              1:1   0027 @0001   argbottom 
1:/mvrtest              1:5   0028 @0002   push $nd 
1:/mvrtest              1:15  0029 @0003   push _KOSArgMarker_ 
1:/mvrtest              1:16  0030 @0004   push $time 
1:/mvrtest              1:21  0031 @0005   push seconds 
1:/mvrtest              1:21  0032 @0006   getmember 
1:/mvrtest              1:29  0033 @0007   push 300 
1:/mvrtest              1:28  0034 @0008   add 
1:/mvrtest              1:33  0035 @0009   push 1 
1:/mvrtest              1:35  0036 @0010   push 1 
1:/mvrtest              1:37  0037 @0011   push 1 
1:/mvrtest              1:37  0038 @0012   call node() 
1:/mvrtest              1:37  0039 @0013   store 
1:/mvrtest              2:1   0040 @0014   push _KOSArgMarker_ 
1:/mvrtest              2:5   0041 @0015   push $nd 
1:/mvrtest              2:5   0042 @0016   call add() 
1:/mvrtest              2:5   0043 @0017   pop 
1:/mvrtest              3:5   0044 @0018   push $nd 
1:/mvrtest              3:8   0045 @0019   push eta 
1:/mvrtest              3:15  0046 @0020   push 600 
1:/mvrtest              3:15  0047 @0021   setmember <<--INSTRUCTION POINTER--
                        0:0   0048         pop 
                        0:0   0049         EOP

Attached save file kOS.zip has a vessel called "kOS Tester" in orbit, which has the mvrtest.ks from above loaded on the local volume of its sole CPU.

[hvacengi]

I have a fix for this prepared and will submit it tonight.