fix: the contacts app's wait for custom NPCs survives a broken NPC in the scene

[r-melvin]

Summary

ContactsAppPatches.WaitForNPCs checked every frame that each physical custom NPC was in the scene. It did this by reading NPC.ID for every result of FindObjectsOfType<NPC>(true). Some of the game's own NPCs throw from ID on IL2CPP: the pooled NPCs/SpecialCustomers/SpecialCustomerNPC(Clone) and SpecialCustomerLeaderNPC(Clone). One throw fails the whole check. On the second load of a session the wait is still running once they exist, so it threw every frame for the rest of the session:

[ERROR] [Il2CppInterop] Exception in IL2CPP-to-Managed trampoline ... NullReferenceException
  at Il2CppScheduleOne.NPCs.NPC.get_ID()
  at S1API.Internal.Patches.ContactsAppPatches.<>c__DisplayClass9_2.<WaitForNPCs>b__6(NPC sn)

That was 1,222 errors in 47 s in one run.

The change.

• Skip broken NPCs: an NPC whose ID throws is skipped. It's never one of the custom NPCs being waited for.
• No nested search: IDs are matched through a set.
• Less often: the check runs four times a second instead of every frame, since it searches the whole scene, inactive objects included.

Compatibility

• Public/protected API: none changed.
• Existing defaults and behavior: the relation circles are added under the same conditions, up to 0.25 s later, and now also when such an NPC is in the scene.
• Stable IDs, saves, and network payloads: none touched.

Validation

Mono

dotnet build S1API.sln -c MonoMelon --no-restore -p:AutomateLocalDeployment=false: 0 errors, 0 warnings. dotnet test ... -c MonoMelon: 743 passed (740 on beta plus 3 new: a throwing NPC id is skipped, a missing NPC is still waited for).

IL2CPP

dotnet build S1API.sln -c Il2CppMelon --no-restore -p:AutomateLocalDeployment=false: 0 errors, 0 warnings. dotnet test ... -c Il2CppMelon: 723 passed (720 plus 3 new).

Runtime evidence

How it was tested. Automated runs on 0.4.7f7 load a save, teleport to each custom NPC, record whether its model is shown and its network state, return to the menu and load again. They used a combined build of #332 to #339.

• Same mods on both runtimes: IL2CPP and Mono "Alternate", with BigWillyMod, The Big Pimpin, Drug Expansion, S1MAPI and SteamNetworkLib. IL2CPP ran without Polyfill, on the game's own interop assembly.
• IL2CPP with about 60 mods: including Polyfill, Siesta and S1UMF.
• Saves: an early save and a late one where The Big Pimpin's intro is played through.

I also played the IL2CPP case by hand.

Before/after on IL2CPP without Polyfill or S1UMF (S1UMF guards NPC.ID itself, which hides the bug). The before build is all of #332 to #339 except this one; the after build is all of them. The probe counted the relation circles in the contacts app.

	First load	Second load	Errors
Without this change	circles for Big Willy and Disco Davey	none	1,560 trampoline errors from WaitForNPCs
With this change	circles for both	circles for both	none

On Mono there were no errors either way.

Documentation

None needed.

🤖 Generated with Claude Code

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[ifBars]

I pushed 9ec0598 to remove the comment that repeated the throwing-ID test. Kept the runtime scan-throttling explanation and XML docs. No runtime changes in this follow-up. Full builds and suites pass: 743 Mono, 723 IL2CPP.

[ifBars]

Tested on 0.4.7f7 Mono and IL2CPP. Dealer and supplier contacts initialized on the first load and after reloading, even with nine scene NPCs throwing when their ID was read.

CI passed. The combined build of #332, #333, #334, #336 and #337 also passed all 770 Mono and 744 IL2CPP tests. Merged into beta.