Fix alert styling using "error" instead of "danger".

There is no "alert-error" style, only "alert-danger" so rewrite the type
to "danger" for correct styling.

Change-Id: Ie812d5bbbbd84a1e9c6d94876c8726124d4fc4e9
Closes-Bug: 1362943
Merge "Fix alert styling using "error" instead of "danger"."