(stable) Fix Phriction rendering for initial install and 404 pages

Summary:
Depends on D19682. Ref T13202. We currently fatal when trying to render a timeline if:

  - an install is fresh, so there are no pages yet, and you look at "/w/"; or
  - you're looking at a Phriction page which doesn't exist (yet) like "/w/aadsflknadsflnf/".

Rendering a timeline and comment area doesn't make sense in these cases, so don't render them.

Test Plan: Hit both cases described above, got "new/empty page" prompts instead of fatals.

Reviewers: amckinley

Maniphest Tasks: T13202

Differential Revision: https://secure.phabricator.com/D19683

src/applications/phriction/controller/PhrictionDocumentController.php

@@ -377,6 +377,7 @@ final class PhrictionDocumentController
       $page_content->setCurtain($curtain);
     }
 
+    if ($document->getPHID()) {
       $timeline = $this->buildTransactionTimeline(
         $document,
         new PhrictionTransactionQuery());
@@ -387,6 +388,10 @@ final class PhrictionDocumentController
 
       $comment_view = $edit_engine
         ->buildEditEngineCommentView($document);
+    } else {
+      $timeline = null;
+      $comment_view = null;
+    }
 
     return $this->newPage()
       ->setTitle($page_title)