Notice: Undefined index: in /srv/mediawiki/php-1.31.0-wmf.29/extensions/Cite/includes/Cite.php on line 767
$group seems to be the non existing index. It has the value " " (regular space, not an insécable/non breakable one).
if ( count( $this->mRefs[$group] ) > 10 ) { $wrapClasses[] = 'mw-references-columns'; }
This occurs when a group doesn't contain any reference, ie when <references group="foo" /> is present, but no <ref group="foo">...</ref> has been declared in the page.
Change 423342 had a related patch set uploaded (by Dereckson; owner: Dereckson):
[mediawiki/extensions/Cite@master] Suppress a notice if a references group doesn't contain any reference
Change 447739 had a related patch set uploaded (by Krinkle; owner: Krinkle):
[mediawiki/extensions/Cite@master] Strengthen referencesFormat() logic by copying before iteration
Change 447739 abandoned by Krinkle:
Strengthen referencesFormat() logic by copying before iteration
Reason:
Not urgent, too complicated. Should be treated treated as legacy debt to to be paid off in a larger refactor at some point.
Change 423342 merged by jenkins-bot:
[mediawiki/extensions/Cite@master] Deal with <references/> inside a <ref> in automatic references list
Change 447839 had a related patch set uploaded (by Krinkle; owner: Krinkle):
[mediawiki/extensions/Cite@wmf/1.32.0-wmf.14] Deal with <references/> inside a <ref> in automatic references list
Change 447839 merged by jenkins-bot:
[mediawiki/extensions/Cite@wmf/1.32.0-wmf.14] Deal with <references/> inside a <ref> in automatic references list