Surprisingly today I get the same error ("Bad File Format") in a new project, no 200 lines of code. The message does not appear when I remove the second skin and weirdly when I do the following check:
you = ent_tiles[(i+1)*tiles_dim_y+j];
if(you == NULL) error("AAA"); // <- this line
your.skill4 = k;
the engine will
not crash which makes zero sense to me.
I can send this project in to the support if wanted.
EDIT: No view entities, just regular ent_created objects.