After I found the cause of a specific extension
interaction bug, brion
pointed out that this was a common error in extensions, that is functions
attached to hooks that do not return a value. Such functions previously
stopped all other functions attached to the hook from running - hence the
interaction issues.
Per r23133, any function that is called by a hook and does not return a
value will through a full stop error. This should encourage new extension
writers to use cleaner functions that avoid this, however, I noticed a lot
extension functions didn't return anything. I grepped through and tried to
fix them all, at least the ones on SVN, but someone else may want to
doublecheck, especially for the ones one WikiMedia sites (mainly
http://en.wikipedia.org/wiki/Special:Version).
I would prefer to have a null return value treated the same as a true
return value. A true return value is almost always what is needed, it
seems to me to make sense to allow this shortcut.
-- Tim Starling