How to show validate error of a node listing page
This may not quite answer your question, but I think it might help with whatever you're trying to do.

You can alter the node creation form to have extra validation and display it on the screen using the devel module, along with a custom module that calls hook_form_alter

function mymodule_form_alter(&amp;$form, &amp;$form_state){
    //add a function in #validate to read form_state and show it on screen
    $form[#validate][] = mymodule_read_values($form_state);
    //or if you want to make it happen before any of the other form validation, uncomment the next line and comment the one above
    //array_unshift($form[#validate], mymodule_read_values($form_state));
}

function mymodule_read_values(&amp;$form_state){
    // make sure you have devel module installed or this will cause WSOD
    dpm($form_state);
    // if you want to prevent form submission you can uncomment the next line
    // throw new Exception('Cancelling form submit - see mymodule');
}


Remember of course, to replace any instance of 'mymodule' with the name of your module, particularly the first one, or the hook won't work.

Doing this will show the structure of the form_state on the screen when you try to save the node.

If you want to target a specific form you can change the first line to 

function mymodule_form_FORMID_GOES_HERE_alter(&amp;$form, &amp;$form_state){