"Error suppression operators have lots of implementation issues in PHP, they are evil and should almost never be used."
"Don't use the error suppression (@) operator for any reason ever. It's broken when E_STRICT is enabled and it causes an unlogged, unexplained error if there is a fatal, which is hard to support. Use wfSuppressWarnings() and wfRestoreWarnings() instead."
Somebody should go through MediaWiki and remove the 87 uses of it and replace it with appropriate error checking. Things like array indexes can be checked with isset(), some things should actually get wfSuppressWarnings() and wfRestoreWarnings() (permission errors on file operations are a good example).
Tagging this easy for somebody with some spare time.