Breaks with ppx_deriving's `show`

[WardBrian]

I was interested in trying this with a large code-base (https://github.com/stan-dev/stanc3) but ran into a few compile-time errors. This seems to be independent of #9, as editing the line in entry.ml has no effect for me.

The simplest error that arises is

File "src/middle/Stan_math_signatures.ml", line 87, characters 29-34:
87 | [@@deriving show {with_path= false}]
                                  ^^^^^
Error: show: boolean expected

I also got a stranger one, which isn't immediately tied to any ppx as far as I can tell:

File "src/common/Foldable.ml", line 66, characters 25-30:
66 |   let any ~pred ?(init = false) x =
                              ^^^^^
Error: This expression has type string option
       but an expression was expected of type int

[jmid]

Thanks for the report! I've looked into the former for a start. #29 should offer a fix.