Notice and warning from panels-add-content-modal.tpl.php.

Thanks for looking into it! Some further thoughts on the patch, which fixes the problem for me ...

+++ b/includes/add-content.incundefined
@@ -43,6 +43,7 @@ function template_preprocess_panels_add_content_modal(&$vars) {
+  $vars['columns'] = array();

We only really need this line to solve the issue, I think.

+++ b/includes/add-content.incundefined
@@ -56,9 +57,7 @@ function template_process_panels_add_content_modal(&$vars) {
-    foreach (range($columns) as $column) {

Strange how this got in the code. Function range() needs at least 2 arguments.

+++ b/includes/add-content.incundefined
@@ -76,12 +75,10 @@ function template_process_panels_add_content_modal(&$vars) {
-  $vars['description'] = isset($vars['content_type']['description']) ? $vars['content_type']['description'] : $title;
+  $vars['description'] = isset($vars['content_type']['description']) ? $vars['content_type']['description'] : $vars['title'];

This is definitely a bug, but maybe it should be addressed in a separate issue/patch?

+++ b/includes/add-content.incundefined
@@ -76,12 +75,10 @@ function template_process_panels_add_content_modal(&$vars) {
-  error_log('test');

It's better not to touch code in your patch that doesn't involve the issue ...

Using Panels 7.x-3.2 on a new-ish site, panels was working fine but today discovered this problem. Not sure when the problem started happening but patch in #3 works for me.

#3 worked for me
Thanks!

Updated issue summary.