--- calendar.module_orig	2012-02-26 14:41:07.803020952 +0900
+++ calendar.module	2012-02-26 14:45:00.383022635 +0900
@@ -141,9 +141,11 @@
     if ($display->display_plugin != 'feed' && !empty($display->display_options['path'])) {
       //$path = $display->display_options['path'];
       $title = $display->display_title;
-      foreach ($display->display_options['arguments'] as $name => $argument) {
-        if (!empty($argument['granularity'])) {
-          $type = $argument['granularity'];
+      if (!empty($display->display_options['arguments'])) {
+        foreach ($display->display_options['arguments'] as $name => $argument) {
+          if (!empty($argument['granularity'])) {
+            $type = $argument['granularity'];
+          }
         }
       }
 
@@ -509,9 +511,11 @@
       }
 
       if ($display->display_plugin != 'feed' && !empty($display->display_options['path'])) {
-        foreach ($display->display_options['arguments'] as $name => $argument) {
-          if (!empty($argument['granularity'])) {
-            $type = $argument['granularity'];
+        if (!empty($display->display_options['arguments'])) {
+          foreach ($display->display_options['arguments'] as $name => $argument) {
+            if (!empty($argument['granularity'])) {
+              $type = $argument['granularity'];
+            }
           }
         }