Custom creature AI update exception that i can't seem to figure from what it's causing it (Fisobs)

[vale wave]

It appears to be from vannila code, but the logs don't show like line number so its very unclear to me, ping me if u got smth to say to fix this

[abstract mica]

Would be useful to know what exactly throws the null reference exception, which can be obtained from logging everything that's referenced in CoordinateCost() and may cause a NRE.

Base game errors in such fundamental functions are very commonly something being passed into as null that's not intended to be, e.g. a room not being baked properly or an invalid attribute being assigned.

[vale wave]

hm i see

let me see if i can overwrite that method to print out what is wrong

@abstract mica like this?

[abstract mica]

pretty much, but with extra logs for everything that can cause a NRE in CoordinateCost

[vale wave]

and what those would be in my case?

[abstract mica]

everywhere where either a . or a [ is used to access a member of a variable in base game's version of CoordinateCost

can't actually open the codebase myself rn

[vale wave]

oh well, i can show the function for u

hmm

maybe its the forbiddenNode that is null? or smth else here i can't figure out? maybe the coord?

[abstract mica]

figuring this out is what logging is for

forbiddenNode being null wouldn't matter though because there's a null check here

[vale wave]

yeah it must be coord

let me run the game

hm, idk if this is bad or not, btw i spawned my creature in a arena for testing @abstract mica

[abstract mica]

shows coord isn't null, hence you need more logs to find out what is null

[vale wave]

hm hmm

maybe 'this.realizedRoom.aimap'?

[abstract mica]

i'd really just log pretty much everywhere where a . is used

it's a temporary log, you can afford to make it spammy

[vale wave]

yeah

rn its kinda like shooting in the dark

oh well

oh it might be

the aimap

[vale wave]

so now with this, @abstract mica, what can you think of my code that is making the aimap null?

ah ofc u had to go offline now grr

:P

[abstract mica]

might be or is certainly null, and is it null specifically in the context where that code would be reached?

[vale wave]

yeah, i put the hook before orig so it would run first, then the vannila code

and it seems like it is

since else the game would freeze and log stuff in the console

[abstract mica]

for example, aimap being null won't matter if InThisRealizedRoom() returns false, since the code path that requires aimap never gets reached

[abstract mica]

this doesn't make sure that aimap being null even matters

the thing you want to know is what causes the null reference exception, and for that the two conditions are being null and having an attribute referenced
this can only establish that it's null and not that the code that references the attribute is reached

[vale wave]

hm, so how do i do that?

[abstract mica]

more logging

if InThisRealizedRoom() returns true in the function, it will return true in the log

if it returns false in the function, it will return false in the log

[vale wave]

hm, so i just hook it up and see if it returns true or false in a situation i know it's being called from CoordinateCost?

[abstract mica]

as I said, you can just spam the log just fine, and you can log as many values as you want at a given time

you can just obtain all information about what everything used in the function is to theoretically trace what path the code takes

the low effort solution I typically had is just e.g. Logger.LogMessage($"{self.forbiddenNode} {coord} {self.forbiddenNode?.value} {self.InThisRealizedRoom(coord)} {self.realizedRoom} <other potential info>"); expanded to cover everything that can matter, whether it's targets of nullref or what determines the path the code takes

then use that to trace what path the code takes and find the first instance of a null that lies in a path the code actually takes, which is the cause of the null reference exception
and then repeat logging with assignments with code related to that variable to find what causes it to take on an unexpected value

[vale wave]

hmm, wait is the sprite creating stuff broken? and its casuing my AI issue? idk man

i think it was this i didn't have a null check, let me see if it will run fine again now

[vale wave]

okay it now works

and everything is magiclly fixed