Throw a checked exception on inconsistent installs.

Allows us to proceed without crashing the system process. Also,
complete an incomplete error message. Follow up comments from
change b904863476991d8540d37d5.

bug: 21144503

(cherry picked from commit c52ae28006605fb2da38b305b60b9bb419aa2f80)

Change-Id: I47b8762449714162fcd5c16eba6fcc146b93120b
1 file changed