Notice: Cannot access property on non-object in /srv/mediawiki/php-1.30.0-wmf.13/includes/specials/SpecialDoubleRedirects.php on line 143
Can you provide more details from the log? Like which object and what property are mentioned?
I think moving line 143 back to the top of the function might solve this (moving it down was not the best idea).
Don't need it, it's obvious from the code -- it's $result https://github.com/wikimedia/mediawiki/blob/master/includes/specials/SpecialDoubleRedirects.php#L143
$titleA = Title::makeTitle( $result->namespace, $result->title );