Basically the errors tells that there is a surface type (much like gravel, tarmac, etc) named graveldark, that is not present in all files. What you could do is to go through the modfiles with the tool Bagedit (in Wreckfest main folder), then then remove any trace of it. Most likely it is added in a file called surfacelist located in data/property/settings as well as the tire file in data/vehicle/sjared/effects

Edit: It is not the 90s Stock car mod that triggers this, but probably a other. If Nascar Legends mod is used you need to use the fix pathches they released later. If you search on the workshop it should be fairly recent addition. Hope this helps :)

For the Nascar Legends patch, make sure that it is below the other mods.

AHHHHHHH, you mean the patch under ALL the mods. Alright, thank you.