Handle/log content handler errors in Updater

Authored by aude on May 19 2017, 1:33 PM.

Description

Handle/log content handler errors in Updater

e.g. pages with invalid/no (longer existing) content handler,
skip indexing and log an error.

Change-Id: I790da98cc864c0946b9f4aed63a3f72825f3cb89