Log and continue when trying to register an invalid event listener

Summary: We currently die if an event listener throws when registering (e.g., because it is misconfigured), but this prevents you from running `bin/config` to fix it, which is a bit silly.

Test Plan: Created this revision with an invalid listener in config.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D6761

src/infrastructure/events/PhabricatorEventEngine.php

@@ -8,7 +8,14 @@ final class PhabricatorEventEngine {
   public static function initialize() {
     $listeners = PhabricatorEnv::getEnvConfig('events.listeners');
     foreach ($listeners as $listener) {
-      id(new $listener())->register();
+      try {
+        id(new $listener())->register();
+      } catch (Exception $ex) {
+        // If the listener does not exist, or throws when registering, just
+        // log it and continue. In particular, this is important to let you
+        // run `bin/config` in order to remove an invalid listener.
+        phlog($ex);
+      }
     }
 
     // Register the DarkConosole event logger.