Change syntax validation processing, part 2

Test the new schema tree logic... And fix bugs in the code.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
ListProcessingReport: be more careful when initiating from another report

As .get{LogLevel(),ExceptionThreshold()} may return null on a ProcessingReport,
take care of checking for this condition before we proceed.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>