Learn English – What does the term “crack-a-lacking” mean

It's not an English word. I don't think it's a mistake either, though. It's more likely to be a jocose usage.

It's an onomatopoeic term for an explosion or perhaps something collapsing in an horrendous cascade of messiness.

Things were going well until lunch, and then a bunch of error reports made my whole day go kerplewy. [My day got messed up badly].

The children's room is kerplewy. [The room is such a mess that explosions are referenced as hyperbole].

It use is normally half-joking, certainly informal.

A variant is kablooie as in "Horrendous Space Kablooie", a term used in a comic for the Big Bang that some scientists prefer. Mostly because they have a sense of humour, but also because "Big Bang" was coined to ridicule the theory, not to name it.