message: Add error handling
message: Add error handling

Some of the methods that can return errors are not being checked for
errors. Check all of the return values where necessary.

Tested:
    Ran through a build and unit test run

Change-Id: I3f8469cbe80a0c58032407f2ba184d913df6e2f1
Signed-off-by: William A. Kennington III <30fff5198f4d10ca1117e5f3ec82f3b4b8900d81@google.com>

openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus