You didn't lose anything that you know about, but that's only because OSX cannot tell when something gets lost. If a single bit were flipped in one of your files, it might look like a typo, or single frame of video with a minor glitch, or it might be a program that crashed for no apparent reason.
I use ZFS, and there aren't errors all that often; only once in the last four years or so. ZFS was able to recover the data and give it to the application, and everything was fine. The only reason I know about it is that ZFS keeps a count of how often it happens on every drive in your system: not very often, but too often.
