Usually when a structure with a structure with a jigsaw that has an error is loaded, the game crashes but when the structure is loaded on world generation (after deleting region files), the game softlocks on the generation screen instead of crashing with last log message being an XML_ERROR_PARSING.

The error i had was a a typo in a blockstate in the "turns into" field

how to reproduce:
-make a new world
-find a village
-log off at the village and delete the region files
-modify the structures from the village you are in to have a jigsaw with an error in the turns_into field (minecraft:grass_block[facing=south] => grass block has to facing property)
-make a datapack out of the structures and place it in the world with a village
-go in the the world with the village (it will regenerate as the region files were destoyed)
-the game should softlock on world generation (at 58% for me)