Catch all exceptions on loadMemo

The contract for loadMemo stipulates that it should
*never* throw an exception, which was not happening.
Now KryoExceptions are caught and logged at WARN but
other exceptions are logged at ERROR.

See gh-1336 and gh-1340, the latter of which likely caused the `IndexOutOfBoundsException` seen in https://github.com/openmicroscopy/bioformats/pull/1340#issuecomment-55577087
Typo in ```failed```