Is a bile jar guaranteed to spawn before map 4's crescendo event in Dark Carnival?

Is a bile jar guaranteed to spawn before map 4's crescendo event in Dark
Carnival?

In Dark Carnival, a bile jar comes in really handy at the end of map 4,
the Farms, for passing the gates and going upstream the flow of zombies
without taking too much damage. Of course, most noobs, if they have a bile
jar, tend to waste it before that critical moment -_-' but that's not the
issue...
My question is: is at least one bile jar guaranteed to spawn before map
4's crescendo event, in every instance of Dark Carnival?