Add missing null to string casts when using rd_fragment and such

These columns are nullable, but the method doesn't accept null.

Found in Logstash.

Change-Id: I3eaafe31005c9319fdd03f8f4b54e7b51ef430f9

includes/api/ApiPageSet.php

@@ -1212,8 +1212,8 @@ class ApiPageSet extends ApiBase {
 				$to = Title::makeTitle(
 					$row->rd_namespace,
 					$row->rd_title,
-					$row->rd_fragment,
-					$row->rd_interwiki
+					$row->rd_fragment ?? '',
+					$row->rd_interwiki ?? ''
 				);
 				$this->mResolvedRedirectTitles[$from] = $this->mPendingRedirectIDs[$rdfrom];
 				unset( $this->mPendingRedirectIDs[$rdfrom] );

includes/jobqueue/jobs/DoubleRedirectJob.php

@@ -234,7 +234,7 @@ class DoubleRedirectJob extends Job {
 					$row->rd_namespace,
 					$row->rd_title,
 					'',
-					$row->rd_interwiki
+					$row->rd_interwiki ?? ''
 				);
 			}
 		}

includes/specials/SpecialBrokenRedirects.php

@@ -121,7 +121,11 @@ class SpecialBrokenRedirects extends QueryPage {
 	public function formatResult( $skin, $result ) {
 		$fromObj = Title::makeTitle( $result->namespace, $result->title );
 		if ( isset( $result->rd_title ) ) {
-			$toObj = Title::makeTitle( $result->rd_namespace, $result->rd_title, $result->rd_fragment );
+			$toObj = Title::makeTitle(
+				$result->rd_namespace,
+				$result->rd_title,
+				$result->rd_fragment ?? ''
+			);
 		} else {
 			$blinks = $fromObj->getBrokenLinksFrom(); # TODO: check for redirect, not for links
 			if ( $blinks ) {

includes/specials/SpecialListRedirects.php

@@ -124,9 +124,11 @@ class SpecialListRedirects extends QueryPage {
 	 */
 	protected function getRedirectTarget( $row ) {
 		if ( isset( $row->rd_title ) ) {
-			return Title::makeTitle( $row->rd_namespace,
-				$row->rd_title, $row->rd_fragment,
-				$row->rd_interwiki
+			return Title::makeTitle(
+				$row->rd_namespace,
+				$row->rd_title,
+				$row->rd_fragment ?? '',
+				$row->rd_interwiki ?? ''
 			);
 		} else {
 			$title = Title::makeTitle( $row->namespace, $row->title );