Invalid program with multiple layers of recursion type checks

[CrowdHailer]

pub fn collapse(id, events) {
  case events {
    [] -> False
    [_, ..rest] -> collapse_thinking(id, rest)
  }
}

pub fn collapse_thinking(id, events) {
  case events {
    [] -> True
    [1, ..rest] -> collapse(id, rest)
    [_, ..rest] -> collapse_checking(id, rest)
  }
}

pub fn collapse_checking(id, events) {
  case events {
    [] -> True
    [1, ..rest] -> collapse_running(id, rest)
    [_, ..rest] -> collapse_thinking(id, rest)
  }
}

pub fn collapse_running(id, _events) {
  echo "running"
  echo id
  let #(a, b) = id
  echo a
  echo b
  echo "done"
  False
}

pub fn main() {
  echo "start"
  collapse(#("a", "b"), [1,2,1])
  collapse(2, [1,2,1])
}

This collapse function should only accept a tuple. The second call in main also type checks, and the program crashes on the line let #(a,b) = id

[GearsDatapacks]

Something weird is definitely going on here. My guess is that it has something to do with the way that mutually recursive functions are type-checked.
The first call to collapse also gives a "unused value" warning, saying that collapse has no side-effects, even though it calls echo

[GearsDatapacks]

Interestingly if you remove collapse_checking, and call collapse_running directly from collapse_thinking, the program seems to type-check as expected (the error appears and the warning goes away)

[lpil]

Oh dear, thank you for the report. Let's try and get this fixed ASAP.

[GearsDatapacks]

I'll take a look at this later