Use PhutilInvalidStateException

Summary: Use `PhutilInvalidStateException`. Depends on D12803.

Test Plan: Unit tests pass.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12829

src/applications/phid/query/PhabricatorObjectQuery.php

@@ -78,7 +78,7 @@ final class PhabricatorObjectQuery
 
   public function getNamedResults() {
     if ($this->namedResults === null) {
-      throw new Exception('Call execute() before getNamedResults()!');
+      throw new PhutilInvalidStateException('execute');
     }
     return $this->namedResults;
   }