The esp32 port sets MICROPY_USE_INTERNAL_ERRNO which causes the built-in list of error codes in py/mperrno.h to be used. That's mostly OK, but there are discrepancies WRT esp-idf (see newlib's errno.h) and lots of missing error codes as a result. Examples:

• MP uses 115 for EINPROGRESS while esp-idf uses 119, this particular one is patched up in exception_from_errno in https://github.com/micropython/micropython/blob/master/ports/esp32/modsocket.c#L156, however esp-idf uses 115 for ENETDOWN, which is now essentially undetectable
• socket operations can return errno 23, which is not defined in MP's list, which means the user has to go on a hunt for where that may be defined to see that it's ENFILE /* Too many open files in system */ (happens, for example, if one doesn't close sockets on error somewhere).
• there are many other useful socket errors which are not in MP's list

Q: is there a reason the esp32 port sets the insufficient MICROPY_USE_INTERNAL_ERRNO other than expediency at the time?