Why extended behavior doesn't work when JS compression is on?

Question

Because old messages with errors doesn't disappear after next, success upload, I want to remove them by this method.

JS file in custom module:

(function ($) {
    /**
     * Attach behaviors to the file upload and remove buttons.
     */
    Drupal.behaviors.fileButtons = {
        attach: function (context) {
            $('input.form-submit', context).bind('mousedown', Drupal.file.disableFields);
            $('div.form-managed-file input.form-submit', context).bind('mousedown', Drupal.file.progressBar);
            $('div.form-managed-file input.form-submit', context).bind('mousedown', function() {
                    $(this).parent().parent().parent().parent().find('.messages').remove();
                });
        },
        detach: function (context) {
            $('input.form-submit', context).unbind('mousedown', Drupal.file.disableFields);
            $('div.form-managed-file input.form-submit', context).unbind('mousedown', Drupal.file.progressBar);
        }
    };
}(jQuery));

module file:

function rpke_forms_form_node_form_alter(&$form, &$form_state) {
    global $conf;
    //$conf['preprocess_js'] = FALSE;
    $form['#attached']['js'][] = drupal_get_path('module', 'rpke_forms') . '/rpke_forms.js';
}

/**
 * Implements hook_module_implements_alter
 */
function rpke_forms_module_implements_alter(&$module_list, $context){
    if($context === 'form_node_form_alter'){
        $temp = $module_list['rpke_forms'];
        // Removing the mymodule key/value
        unset($module_list['rpke_forms']);
        // Adding the mymodule key value as the last member in the list
        $module_list['rpke_forms'] = $temp;
    }
}

Everything works as expected when JS compression is off, after enabling, it stops working. It's works all time, when I uncomment $conf['preprocess_js'] = FALSE;