Fix display of current file on Macro creation

Summary: This could hit an obscure fatal.

Test Plan:
  - Create a macro.
  - Upload a file, but don't give it a name.
  - Before: fatal.
  - After:

{F2569846}

Reviewers: chad, 20after4

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D17310

src/applications/macro/controller/PhabricatorMacroEditController.php

@@ -185,6 +185,7 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
     if (!$macro->getID()) {
       if ($current_file) {
         $current_file_view = id(new PhabricatorFileLinkView())
+          ->setViewer($viewer)
           ->setFilePHID($current_file->getPHID())
           ->setFileName($current_file->getName())
           ->setFileViewable(true)