[RFC][VOTE] Throwable error code's type generalization

Hi Marco \o,

linking to the discussion thread http://externals.io/thread/573 because I
don't have much more to add.

I think the throwable's code is almost never used regardless, but this
could give users more opportunities to do something useful with it as
Niklas stated in previous thread.

Changing PDO errors to be int is an option, too, but I don't see that
happening, not even in a major version. It would be a huge non-bc change
for very very little improvement...

This instead could open up to new uses for the property, that again is
barely used these days, while also fixing the PDO inconsistency.

Exception#getCode() is mostly used when re-throwing exceptions as
different exception types, and the API naming makes for very hard searches
for usages on Github too.

In doctrine, we use it to exactly to decide what to throw (specific
exception type).

If you are saying that getCode is mostly unused, consider proposing a
deprecation RFC instead, and provide an API specific to your use case as a
replacement.

linking to the discussion thread http://externals.io/thread/573 because I
don't have much more to add.

I think the throwable's code is almost never used regardless, but this
could give users more opportunities to do something useful with it as
Niklas stated in previous thread.

Hi Wes,

why did you go for mixed instead of string|int? Error codes being
objects still doesn't make sense to me.

Regards, Niklas