#156392 by iacopopecchi, patch by myself: tracker module depends on comment module (uses its tables and constants without checking for the module being present), so this dependency should be codified in the .info file

modules/tracker/tracker.info

@@ -1,6 +1,7 @@
 ; $Id$
 name = Tracker
 description = Enables tracking of recent posts for users.
+dependencies[] = comment
 package = Core - optional
 version = VERSION
 core = 6.x

modules/tracker/tracker.module

@@ -101,7 +101,7 @@ function tracker_page($uid = 0) {
   while ($node = db_fetch_object($result)) {
     // Determine the number of comments:
     $comments = 0;
-    if (module_exists('comment') && $node->comment_count) {
+    if ($node->comment_count) {
       $comments = $node->comment_count;
 
       if ($new = comment_num_new($node->nid)) {