Filter bug

When trying to submit a new microcontent node, I get this

Fatal error: Cannot use string offset as an array in D:\dev\drupal-4.7.0\modules\filter.module on line 842
Call Stack
# Function Location
1 {main}() D:\dev\drupal-4.7.0\index.php:0
2 menu_execute_active_handler() D:\dev\drupal-4.7.0\index.php:15
3 call_user_func_array () D:\dev\drupal-4.7.0\includes\menu.inc:418
4 node_page() D:\dev\drupal-4.7.0\includes\menu.inc:0
5 node_add() D:\dev\drupal-4.7.0\modules\node.module:1995
6 node_form() D:\dev\drupal-4.7.0\modules\node.module:1711
7 drupal_get_form() D:\dev\drupal-4.7.0\modules\node.module:1584
8 form_builder() D:\dev\drupal-4.7.0\includes\form.inc:115
9 node_form_add_preview() D:\dev\drupal-4.7.0\includes\form.inc:434
10 drupal_validate_form() D:\dev\drupal-4.7.0\modules\node.module:1667
11 _form_validate() D:\dev\drupal-4.7.0\includes\form.inc:176
12 call_user_func_array () D:\dev\drupal-4.7.0\includes\form.inc:243
13 filter_form_validate() D:\dev\drupal-4.7.0\includes\form.inc:0