php fatal shutdown_function debugger

function debug_string_backtrace() {
    $output = '';
    $backtrace = debug_backtrace();
    foreach($backtrace as $key => $item) {
      $output .= "\r\n item $key ".$item['file']." [".$item['line']."] ".$item['function'];
    }
    return $output;
}

error_reporting(E_ERROR);
function fatal_handler() {
  // $errfile = "unknown file";
  // $errstr  = "shutdown";
  // $errno   = E_CORE_ERROR;
  // $errline = 0;

  $error = error_get_last();

  if( $error !== NULL && $error['type'] == E_ERROR) {
    $errno   = $error["type"];
    $errfile = $error["file"];
    $errline = $error["line"];
    $errstr  = $error["message"];
    error_log("TRAPPED --> $errno $errfile $errline $errstr");
    error_log( debug_string_backtrace() );  //
   // error_log( implode(" ** ", debug_backtrace( false )) );

  }
  //exit(0);
  //error_mail( format_error( $errno, $errstr, $errfile, $errline ) );
}

register_shutdown_function( "fatal_handler" );