Simplify code to set up output parser chain a bit

It is save to set 0 as a parser.

Change-Id: I57e9a6e2c3c4661356b5b79371946edad367888a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
OutputParser: Simplify detection of fatal errors a bit.

Change-Id: I46f6942a8bee8a1c9711dc97db6424893dd3f276
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>