diff --git a/src/applications/differential/xaction/DifferentialRevisionCloseTransaction.php b/src/applications/differential/xaction/DifferentialRevisionCloseTransaction.php
--- a/src/applications/differential/xaction/DifferentialRevisionCloseTransaction.php
+++ b/src/applications/differential/xaction/DifferentialRevisionCloseTransaction.php
@@ -46,10 +46,12 @@
   }
 
   protected function validateAction($object, PhabricatorUser $viewer) {
-    if ($this->getEditor()->getIsCloseByCommit()) {
-      // If we're closing a revision because we discovered a commit, we don't
-      // care what state it was in.
-      return;
+    if ($this->hasEditor()) {
+      if ($this->getEditor()->getIsCloseByCommit()) {
+        // If we're closing a revision because we discovered a commit, we don't
+        // care what state it was in.
+        return;
+      }
     }
 
     if ($object->isClosed()) {
diff --git a/src/applications/transactions/storage/PhabricatorModularTransactionType.php b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
--- a/src/applications/transactions/storage/PhabricatorModularTransactionType.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
@@ -134,6 +134,10 @@
     return $this->editor;
   }
 
+  final protected function hasEditor() {
+    return (bool)$this->editor;
+  }
+
   final protected function getAuthorPHID() {
     return $this->getStorage()->getAuthorPHID();
   }