Zig is pretty spot on here.
Probably, at least the first 3 years your cat is more of a threat to your snake.
A good keeper rarely has escapes. You will be fine and so will the other animals.
An IJ would need to be HUGE to think of a cat as prey. My coastal mutt is about 6.5 feet long and a cat with claws would destroy her at this stage.
As Zig stated, its the larger, older snakes that could possibly be a threat.
I think a lottery win or a lightning strike is about the same odds as your cat being constricted by a snake like an IJ.
I doubt you'd leave the cage open anyhow.