I'm crashing on embark, too. Here's my error log:
Duplicate Object: creature GIANT_WORM_STRIFE
Duplicate Object: item ITEM_TOY_CHESSBOARD
*** Error(s) found in the file "data/save/region1/raw/objects/creature_random_myth_beast_standard_mdf.txt"
SEAL_ANIMAL_WEEVIL BP Add Type GELDABLE Was Not Used
SEAL_ANIMAL_WEEVIL BP Add Type GELDABLE Was Not Used
SEAL_ANIMAL_WEEVIL BP Add Type GELDABLE Was Not Used
*** Error(s) finalizing the creature GHOUL_CAVE
undefined local creature material set to default: GHOUL_CAVE SKIN
*** Error(s) finalizing the creature BEAST_CINDER
undefined local creature material set to default: BEAST_CINDER SKIN
*** Error(s) finalizing the creature BEAST_SHADOW
undefined local creature material set to default: BEAST_SHADOW SKIN
*** Error(s) finalizing the creature OGRE_DUSK
undefined local creature material set to default: OGRE_DUSK SKIN
*** Error(s) finalizing the creature MERROWS
undefined local creature material set to default: MERROWS SKIN
*** Error(s) finalizing the creature EFREET
undefined local creature material set to default: EFREET SKIN
*** Error(s) finalizing the creature STAR_SHAMBLER
undefined local creature material set to default: STAR_SHAMBLER CHITIN
*** Error(s) finalizing the creature LIZARD_SAILFIN
undefined local creature material set to default: LIZARD_SAILFIN SKIN
*** Error(s) finalizing the entity NAGA
Unrecognized entity toy token: ITEM_TOY_TOY
Update: It's only happening when I try to set up in an evil biome.