When selecting an entire structure (in this case water_room or with_signs) loaded into the world and setting it to air or dirt, Minecraft would crash shortly after with:
java.lang.IllegalArgumentException: Cannot get property bbc{name=facing, clazz=class dz, values=[north, east, south, west]} as it does not exist in baq{block=minecraft:air, properties=[]}
However, after removing the 4 signs from the structure, Minecraft would not crash when I use /fill on the whole structure.
The Data Pack attached has 3 structures: water_room, with_signs and without_signs. water_room and with_signs should be the same.
Game Output Log: https://pastebin.com/ASvPVeCc
Crash Report: https://pastebin.com/rdw3dkW7
Structures generated in 1.12 or lower are not going to be able to be loaded in 1.13+ sadly 😞