commit 417aeca48d6362d3c58c89aa51347baf7dcdbaef
Author: Lee Rowlands <lee.rowlands@previousnext.com.au>
Date:   Thu Jun 20 10:25:45 2013 +1000

    Fix some uninstall woes

diff --git a/core/modules/comment/comment.install b/core/modules/comment/comment.install
index 3a7f7f4..0498ac0 100644
--- a/core/modules/comment/comment.install
+++ b/core/modules/comment/comment.install
@@ -12,7 +12,9 @@
  */
 function comment_uninstall() {
   // Delete comment_body field.
-  field_info_field('comment_body')->delete();
+  if ($field = field_info_field('comment_body')) {
+    $field->delete();
+  }
 
   // Remove variables.
   variable_del('comment_block_count');
diff --git a/core/modules/forum/forum.install b/core/modules/forum/forum.install
index d779dee..070818e 100644
--- a/core/modules/forum/forum.install
+++ b/core/modules/forum/forum.install
@@ -133,7 +133,9 @@ function forum_uninstall() {
   // Delete comment field, load comment in case it has been disabled.
   drupal_load('module', 'comment');
   // Remove the forum comment field.
-  field_info_field('comment_node_forum')->delete();
+  if ($field = field_info_field('comment_node_forum')) {
+    $field->delete();
+  }
 
   // Purge field data now to allow taxonomy and comment modules to be
   // uninstalled if these were the only fields remaining. We need to call