Add a generic error message for missing vendor error strings.

The message is empty, instead of null, to prevent apps from crashing but it will be changed to a more meaninful string in a future change.

Fix: 196176475
Test: N/A
Change-Id: I7823084238a87cb1b8892b8550c472cd8b40f556
(cherry picked from commit 5d5d9eb8122b33705a864a1946da479af2bd10db)
2 files changed