$this->namespaceNames = self::$dataCache->getItem( $this->mCode, 'namespaceNames' );
$validNamespaces = MWNamespace::getCanonicalNamespaces();
+ /** @suppress PhanTypeInvalidLeftOperand */
$this->namespaceNames = $wgExtraNamespaces + $this->namespaceNames + $validNamespaces;
$this->namespaceNames[NS_PROJECT] = $wgMetaNamespace;