Ajax comment in dpm and unset

Hi
In the comments, i have a custom module with a hook_node_view_alter
and i have a unset and generate this error when active the module

Fatal error: Cannot unset string offsets in /modules/custom/.... on line 36 Call Stack: 0.0004 662992 1. {main}() /usr/share/nginx/www/7a5/index.php:0 0.5356 80271096 2. menu_execute_active_handler() /----/nginx/www/--/index.php:26 0.5357 80272288 3. call_user_func_array() /---/nginx/www/--/includes/menu.inc:517 0.5357 80272776 4. node_page_view() /includes/menu.inc:517 0.5361 80289656 5. node_show() /node.module:2653 0.5361 80290304 6. node_view_multiple() node/node.module:1418 0.5445 81050392 7. node_view() modules/node/node.module:2582 0.8263 102208872 8. drupal_alter() /modules/node/node.module:1307 0.8267 102215816 9. hook_node_view_alter() includes/module.inc:1056