Game Crash When Fighting Celestial Champion with Merms

Disabled all server mods, but the crash still happens. It seems to occur shortly after the Celestial Champion's first attack, but it happens consistently.

It also seems to occur when fighting the Ancient Fuelweaver.

Happens when using the merms to fight Deadly Brightshade too. Server crash.

Backtrace:
[00:15:57]: Could not find anim [breach_pst] in bank [lunarthrall_plant_vine_big]
[00:16:07]: [string "scripts/components/combat.lua"]:1028: attempt to index a nil value
LUA ERROR stack traceback:
scripts/components/combat.lua:1028 in (method) CalcAttackRangeSq (Lua) <1027-1030>
   self =
      hiteffectsymbol = marker
      defaultdamage = 100
      lasttargetGUID = 140369
      forcefacing = true
      ignorehitrange = false
      inst = 139273 - lunarthrall_plant (valid:true)
      retargetperiod = 1
      hitrange = 3
      lastdoattacktime = 844.80004405975
      lastwasattackedbytargettime = 0
      lastwasattackedtime = 845.03337740526
      keeptargettimeout = 1
      transfertargetcallback = function - scripts/components/combat.lua:81
      keeptargetfn = function - scripts/prefabs/lunarthrall_plant.lua:380
      externaldamagetakenmultipliers = table: 0x315ddc30
      laststartattacktime = 0
      retargettask = PERIODIC 139273: 1.000000
      targetfn = function - scripts/prefabs/lunarthrall_plant.lua:314
      lastattacker = 140562 - merm_shadow (valid:true)
      losetargetcallback = function - scripts/components/combat.lua:80
      battlecryenabled = true
      _ = table: 0x37627360
      externaldamagemultipliers = table: 0x359774a0
   target = nil
scripts/brains/mermguardbrain.lua:267 in (field) target_dist_fn (Lua) <260-268>
   inst = 140365 - mermguard_shadow (valid:true)
   target = 139273 - lunarthrall_plant (valid:true)

 

I encountered this exact same bug many times today in a community server partly under my administration, and also after reproducing it on my own world, modless.
I was going to submit a report, but noticed this post, so decided to add my own experience to here

based on the crash logs I suspect it has to do with a particular choice from wurt's skillet:

Quote

scripts/behaviours/follow.lua:47 in (method) EvaluateDistances (Lua) <39-49>

self =

action = BACKOFF

This leads me to believe the crash is related to the behaviour of merms retreating combat when they get hurt, which is part of the skillset. I'm not entirely certain if this is the leading cause to the crash, though.
However it does seem that the mob always involved with this crash is "Mermguard".
As for the mermguard's target, so far i've seen it happen on multiple targets: "mermguard, tentacle, merm"
Some conditions mentioned in this post were not needed to replicate the crash, however it seems that these conditions are vital to make the crash occur:

• This skilltree: the red outlined skills is what I suspect to be a likely culprit
• Allied (not mutated) mermguards (with armour) fighting with tentacles, among other creatures;
• The mermguards reaching low health and needing to retreat

A few other details that might be helpful to know, one of which is the same as the original post:

• A large number of merm guards/warrior merms
• a merm king being alive

I have included my server log of replicating the crash. It seems that the entire error stack traceback is identical.

@neemias12 I do wonder what are your choices for wurt's skilltree when this happened? It seems likely that one of the chosen skills are leading up to this crash.

server_log.txt

I tried to kill the moon champion. Character: Wurt (shadow part of the talent tree). For unknown reasons, there are crashes after the death of shadow merms, please fix it

Changed Status to Fixed