`nickel doc` overflows the stack with recursive schemas

[yannham]

Describe the bug nickel doc aborts with a stack overflow on a real-world 1MB Nickel schema, which doesn't look very deep (nickel doc does use recursive calls, but the stack space should be linear in the depth of the schema, roughly).

To Reproduce I unfortunately can't provide the test case, which has been provided as a courtesy but isn't public. This issue is mostly a reminder to investigate it.

[yannham]

We do have a MRE, and it seems it doesn't have anything to do with schema size, but everything to do with recursive contracts:

{
  Recursive = {
    foo | Number,
    bar | Recursive | optional
  }
}