Improve JSON_USE_EXCEPTION=0 workflow

[baylesj]

Is your feature request related to a problem? Please describe.
Currently, JSON_USE_EXCEPTION=0 results in abort() calls instead of exception throwing, which may be undesirable for some clients.

Describe the solution you'd like
A more rigorous solution allowing the client to determine if they want to abort, or just ignore/retry/handle the error some other way.