When triggered either by becoming master, a new cluster state, or a
periodic schedule, an ILM policy execution through
`maybeRunAsyncAction`, `runPolicyAfterStateChange`, or
`runPeriodicStep` throwing an exception will cause the loop the
terminate. This means that any indices that would have been processed
after the index where the exception was thrown will not be processed by
ILM.
For most execution this is not a problem because the actual running of
steps is protected by a try/catch that moves the index to the ERROR step
in the event of a problem. If an exception occurs prior to step
execution (for example, in fetching and parsing the current
policy/step) however, it causes the loop termination previously
mentioned.
This commit wraps the invocation of the methods specified above in a
try/catch block that provides better logging and does not bubble the
exception up.
680436dd0d