The most common error would be ENOATTTR, which means no such attribute was set. We definately want to ignore this. Other errors are ENOTSUP if the source fs doesn't support extended attributes, I doubt we want to report that.

In general, i don't think there is really any error here that are useful to report. If there is a readable xattr we want to store it, otherwise its for all intents an purposes as if it wasn't anything there.