Hello,
I have also been encountering this problem, though the rarity of spices means that it is not a major problem. I get the same (or very similar) errors, but they can cause crashes. You can Alt-Tab to the error message and close it down but later on it caused crashes as my save-file got bigger, as minimising games is somewhat unreliable.
Out of curiosity I looked in native M&B and Brytenwalda Repolished texture folders, but could not find the spice textures yet to my knowledge, I never encountered problems with spices. I had this problem with grain, but downloading Brytenwalda Reworked again fixed it.
One town (Caer Luit Coyt or Llys Pengwern) that belongs to the yellow faction just past the river on the Welsh border seems to use spice textures in the lord's hall, causing the error message to appear.
Finally, my faction is hostile to neutrals - including cattle. I was escorting some cattle for a guild master when one of my lords arrived and attacked them, in a desperate attempt to save his liege from the fearsome cattle. I joined in the battle and discovered that cattle are actually naked men with no gear whatsoever. As it turns out cattle are slaves... do not butcher cattle for meat... Our heavy cavalry mowed them down in a slaughter to rival fighting Sarranids. Unfortunately it led to endless errors messages in the game log, so I had to reload a previous save.
Thanks for all the hard work on Brytenwalda.