Fix an issue with handling of null feed URIs

Summary: Ref T8658. Caught this in the logs. This value may be set to `null`. Handle that gracefully.

Test Plan: Will check logs.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8658

Differential Revision: https://secure.phabricator.com/D13432

src/applications/feed/worker/FeedPublisherWorker.php

@@ -6,6 +6,8 @@ final class FeedPublisherWorker extends FeedPushWorker {
     $story = $this->loadFeedStory();
 
     $uris = PhabricatorEnv::getEnvConfig('feed.http-hooks');
+
+    if ($uris) {
       foreach ($uris as $uri) {
         $this->queueTask(
           'FeedPublisherHTTPWorker',
@@ -14,6 +16,7 @@ final class FeedPublisherWorker extends FeedPushWorker {
             'uri' => $uri,
           ));
       }
+    }
 
     $argv = array(
       array(),