Add more error checking for mctimings

Change-Id: I96a85310bd48180c03919cdc398d2bbd8a27321c
Reviewed-on: http://review.couchbase.org/35935
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>