Diffusion - return 404 errors for bad URIs

Summary: Fixes T5646. Makes diffusion a much better user experience. Users now see a 404 exception page when they have a bad URI. Previously, they saw a developer-facing raw exception.

Test Plan: played around in diffusion a bunch. most of these changes were fairly mechanical at the end of the day.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T5646

Differential Revision: https://secure.phabricator.com/D11299

src/applications/diffusion/controller/DiffusionPushEventViewController.php

@@ -3,23 +3,16 @@
 final class DiffusionPushEventViewController
   extends DiffusionPushLogController {
 
-  private $id;
-
   public function shouldAllowPublic() {
     return true;
   }
 
-  public function willProcessRequest(array $data) {
-    $this->id = idx($data, 'id');
-  }
-
-  public function processRequest() {
-    $request = $this->getRequest();
+  protected function processDiffusionRequest(AphrontRequest $request) {
     $viewer = $request->getUser();
 
     $event = id(new PhabricatorRepositoryPushEventQuery())
       ->setViewer($viewer)
-      ->withIDs(array($this->id))
+      ->withIDs(array($request->getURIData('id')))
       ->needLogs(true)
       ->executeOne();
     if (!$event) {