Double Dark Side! Diesel & 8P
VCDS doesn't normally show an error if the door contact is faulty. That error suggests that your alarm has been set off by one of the interior sensors.
The tell tale signs of the door contact are the interior lights not switching off when the door is closed and the DIS showing that the door is open when it isn't.
With the full version of VCDS you can see the output of the door/boot/bonnet switches. "0" means the door is open and "1" means the door is closed. This is another way to check if the switches are ok.
The error regarding the possible leaky pump is very common on these cars. I have a reconditioned central locking pump and mine still throws up that error sometime. As long as the central locking is still working I wouldn't worry too much.