Index: javascript_aggregator.module
=========================================================
--- javascript_aggregator.module	(revision 1.17.2.16)
+++ javascript_aggregator.module	Tue Apr 13 16:45:03 CEST 2010
@@ -47,7 +47,7 @@
 function javascript_aggregator_theme_registry_alter(&$theme_registry) {
   if (isset($theme_registry['page'])) {
     // If javascript_aggregator's preprocess function is there already, remove it.
-    if ($key = array_search('javascript_aggregator_preprocess_page', $theme_registry['page']['preprocess functions'])) {
+    if (is_array($theme_registry['page']['preprocess functions']) && $key = array_search('javascript_aggregator_preprocess_page', $theme_registry['page']['preprocess functions'])) {
       unset($theme_registry['page']['preprocess functions'][$key]);
     }
     // Now tack it on at the end so it runs after everything else.