+ stderr_tracer doesn't trace statement preparation [2.4.0]

  If a statement is invalid, then it will fail during preparation. However,
  currently, there is no way to see that statement since stderr_tracer doesn't
  trace this event.

  Options:

  * trace preparation by default - too much info
  * allow changing behavior at runtime - not thread safe
  * support via bool flag and make user instantiate - burdensome
  * support via bool flag and instantiate stderr_full_tracer - code bloat
    but seems the best option