Last modified: 2011-11-22 15:46:52 UTC
See URL. An "element is null" (wikibits.js, line 1063, addHandler) is thrown. This function is called by an inline script, document.getElementById( 'mw-abusefilter-examine-test' ) returned null, but didn't check this and so handed on null to addHandler which caused this error.
Note that the trunk code uses jQuery to add this handler and would fail silently (without an error) in case the element's missing -- but the 1.18 code has not yet been changed in this way. No idea offhand what the element's for or what it does so don't know why it would be missing or if that's a problem on its own.
Still not fixed after 1.18 deployment. Lowering priority.
This should be fixed in trunk since I've rewritten the JS for AbuseFilter.