where can I display the error back from server Ajax REST requests ?

idealcoms

I edited this question to focus on a specific business case :

I am sending and processing correctly the client/server Ajax REST requests, but upon error ( generic) when sending back correctJSON response , nothing is displayed in the Editor form ...

@data = {error: "a notification"}
render json: @data.to_json , status: 403    #Forbidden Attributes

the ajax response is , detected correctly in my editor
but where and how can I display this error ? ( in the form ?)
and can I close the form programmatically ?

EDIT error!

returned: {
  "readyState": 4,
  "responseText": "{\"error\":\"Sorry forbidden attributes. Please contact your system admin.\"}",
  "responseJSON": {
    "error": "Sorry forbidden attributes. Please contact your system admin"
  },
  "status": 403,
  "statusText": "Forbidden"
}

Here is my editor setup

editor = new $.fn.dataTable.Editor( {
      ajax:{
        ...
        edit: {
          type: 'PUT',
          dataType : "json",
          success: function (json) {
            console.log("EDIT success!");
            console.log("returned json: "+JSON.stringify(json, null, 2));
            //success( json );
          },
          error: function (xhr, error, thrown) {
            console.log("EDIT error!");
            console.log("returned: "+JSON.stringify(xhr, null, 2));
            //error( xhr, error, thrown );
          }
        },
...