test: attempt to add test for printexn issue

[jchavarri]

No description provided.

[anmonteiro]

I implemented exn_slot_id in the runtime (which wasn't implemented since exceptions moved to being a record).

but there are some builtin exceptions for which it'll return -1, because e.g. in stdlib.js var Not_found = "Not_found" for example.

[jchavarri]

there are some builtin exceptions for which it'll return -1, because e.g. in stdlib.js var Not_found = "Not_found" for example.

I guess this is ok? Assuming the only purpose of these functions is to print / log exceptions, and not something else 🤔 I have never used these functions tbh.

There are some test failures related to the change:

File "/build/source/_build/default/jscomp/runtime/caml_exceptions.ml", line 92, characters 14-29:
92 |   let parts = Js_string.split "/" x.id in
                   ^^^^^^^^^^^^^^^
Error: Unbound module Js_string

[anmonteiro]

I guess this is ok?

I think it's OK, just that the results between OCaml / JS won't be reliably equal (or at all).