Exception occured while saving ScenarioModule 'ContractVesselTracker'

[Pau-Already]

The following occurred during a non-ro/rp1 modded career.

Exception occured while saving ScenarioModule 'ContractVesselTracker':
System.NullReferenceException: Object reference not set to an instance of an object
  at ContractConfigurator.Extensions+<>c__DisplayClass5_1.<GetHashes>b__1 (ProtoPartSnapshot childPart) [0x00000] in <5f43a800affb4f318f640e019f093598>:0 
  at System.Linq.Enumerable+WhereListIterator`1[TSource].MoveNext () [0x00037] in <351e49e2a5bf4fd6beabb458ce2255f3>:0 
  at System.Linq.Enumerable.TryGetFirst[TSource] (System.Collections.Generic.IEnumerable`1[T] source, System.Boolean& found) [0x00045] in <351e49e2a5bf4fd6beabb458ce2255f3>:0 
  at System.Linq.Enumerable.FirstOrDefault[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x00000] in <351e49e2a5bf4fd6beabb458ce2255f3>:0 
  at ContractConfigurator.Extensions+<GetHashes>d__5.MoveNext () [0x00320] in <5f43a800affb4f318f640e019f093598>:0 
  at System.Linq.Enumerable.Contains[TSource] (System.Collections.Generic.IEnumerable`1[T] source, TSource value, System.Collections.Generic.IEqualityComparer`1[T] comparer) [0x00036] in <351e49e2a5bf4fd6beabb458ce2255f3>:0 
  at System.Linq.Enumerable.Contains[TSource] (System.Collections.Generic.IEnumerable`1[T] source, TSource value) [0x0000a] in <351e49e2a5bf4fd6beabb458ce2255f3>:0 
  at ContractConfigurator.ContractVesselTracker+<>c__DisplayClass17_0.<OnSave>b__1 (Vessel v) [0x0000f] in <5f43a800affb4f318f640e019f093598>:0 
  at System.Collections.Generic.List`1[T].Find (System.Predicate`1[T] match) [0x0000d] in <9577ac7a62ef43179789031239ba8798>:0 
  at ContractConfigurator.ContractVesselTracker.OnSave (ConfigNode node) [0x00060] in <5f43a800affb4f318f640e019f093598>:0 

For context, this window popped up when making a save after an orbital docking event between 'Module 1' and 'Module 2.' Module 2 has already had Module 3 docked to it, and Module 4 docked with 3. In the save file Module 1 was a subject of ContractVesselTracker

	{
		name = ContractVesselTracker
		scene = 7, 8, 5
		VESSEL
		{
			key = Eve Express Launcher
			id = bc5c1472-998f-47b0-8e7c-990a7fb93a83
			hash = 1231180592
		}
	}

Module 1 (with a Cupola as a root part, and other crewable parts) was also the subject vessel of an available contract to crew a station.
Module 2 has as its root part a structural piece (NearFutureConstruction Octagonal Truss), modules 2,3,4 were probe controlled without crew spots.

After docking, VESSEL(Eve Express Launcher) doesn't appear in SCENARIO(ContractVesselTracker), but the contract is still active.

[Pau-Already]

I believe the contract comes from "Contract Pack: Bases and Stations Reborn"

[Tallinu]

I just ran into this when quick-saving right after completing a contract to adjust or verify the station-keeping of my first plane of KPS satellites (from Contract Pack: Constellations). Looks like the same exception, only different in a few of those big hex values in angle brackets.
I'd been jumping around between ships completing other tasks before switching to those six satellites in turn to get that contract out of the way (while quicksaving before each vessel switch or return-to-space-center in case of the inevitable crash, as I have quite a few mods running and I was honestly surprised it hadn't happened already due to the number of launches and vessel switches I'd done by that point).

CC Displayed Exception.txt
KSP log shortly after ContractConfigurator error.log
savefiles.zip
ModsList.txt
ModsCKAN.zip

Don't know if the saves and such are helpful, but I figured just in case... (The 'Backup' folder has several of the quick-saves prior to completing that contract and the one for which the error was generated, I believe.)

[siimav]

So it appears that the first instance of the exception follows this:

[LOG 01:16:34.811] [Vessel KPS Marker A1]: Vessel was destroyed.
[LOG 01:16:34.811] [Vessel KPS Marker A2]: Vessel was destroyed.
[LOG 01:16:34.811] [Vessel KPS Marker A3]: Vessel was destroyed.
[LOG 01:16:34.812] [Vessel KPS Marker A4]: Vessel was destroyed.
[LOG 01:16:34.812] [Vessel KPS Marker A5]: Vessel was destroyed.

I assume those are some kind of vessels that got automatically destroyed on contract completion?
Is the screenshot taken right after contract completion or were there any scene changes in between?

[Tallinu]

There were no scene changes between the contract completion and the error. The only thing that took place in between contract completion and the save attempt 2-3 seconds later was clearing the last two notifications it had generated.

There's also an A6 that should've been destroyed. (Dang, the log has 12 (6?) exceptions and does not list it as destroyed.) I'll have to check my game and see if it got left behind.

Those (A1-A6) are the constellation position marker "vessels" that have no parts and are spawned by the contract so you can easily position each satellite at the correct point on the orbit. It seems there's no way to specify a mean anomaly in contracts, so the author used these phantom vessels which you can simply rendezvous with and then fine tune from there. Works great gameplay-wise.

This is the first time I've seen any error. Although in the forum post (I linked it earlier) they did mention under Dependencies, "Contract Configurator v2.10.0.0 (relatively recent version, I had to add a few things to make this pack work)"... I wonder if whatever was added at that time would be a good place to start, or a wild goose chase?

[siimav]

This raises suspicions:

[LOG 22:50:05.292] [Grapple Module] Grabbing on to Ast. XDC-760 F on Ast. XDC-760 F

ContractConfigurator/source/ContractConfigurator/Util/Extensions.cs

Lines 221 to 222 in eef2551

	ModuleGrappleNode grapple = pm.moduleRef as ModuleGrappleNode;
	ProtoPartSnapshot dockedPart = parts.Where(childPart => childPart.flightID == grapple.dockedPartUId).FirstOrDefault();

Looks like you used the grappling part just before getting the CC exception? Not entirely out of the question that pm.moduleRef can be null in some circumstances.

[Tallinu]

Well, I had been in the process of maneuvering a couple asteroids and capturing another, prior to switching to the KPS satellites to do that station-keeping contract. It wasn't exactly "just before" -- I hadn't returned to the space center, but I had switched through at least six other vessels (each of the KPS satellites in turn) prior to completing that contract, quicksaving again (I save before every vessel switch), and having that error generated by the saving process.

The grapple was on a vessel which was not involved in any contract. Why would ContractConfigurator have tried to reference that vessel at that time? If it was trying to look at the grappled object from six-plus scenes ago, I wonder if that might be an issue worth looking into... Some combination of the grappler and asteroid no longer being the current vessel and a contract having completed triggering it on next save, maybe?

RE my previous comment, I don't see any sign in my save file or tracking station of an A6 marker left un-destroyed, the completed station-keeping contract does have all six tasks marked, and the six satellites involved all do seem to be correctly listed as tracked for the contract chain still. Nothing appears to have been messed up there, at least.

[siimav]

Welp, the best I can do for now is push out a release that hopefully has some more details the next time someone manages to reproduce this issue.

[siimav]

#61 confirmed my theory that grappling partmodule can cause this issue. A release has been pushed out to fix this. If no further reports show up for this issue then we can consider it resolved.