Fix "Undefined index" notices in ApiMobileView

ApiMobileView#getData returns an empty array if the title redirects to a
page in a virtual namespace (NS_SPECIAL, NS_MEDIA). Protect against
"Undefined index" notices when generating the response.

Bug: 73109
Change-Id: I3005453645daf205523c2640b6e5be77a91e6a69
Merge "Fix "Undefined index" notices in ApiMobileView"