PHP Custom Error Handler

<?php
//error handler function
function customError($errno, $errstr, $fileName, $lineNo)
{
 switch ($errno) {
  // fatal error. die it.
  case E_USER_ERROR:
   echo "<b>Error:</b> [$errno] $errstr<br />";
   echo "Ending Script<br>";
   // Fatal err. so mail to web master.
   //error_log("Error: [$errno] $errstr", 1, "someone@example.com","From: webmaster@example.com");
   die();
   break;
  case E_USER_WARNING:
    echo "<b>My WARNING</b> [$errno] $errstr<br />n";
          break;
  case E_USER_NOTICE:
    echo "<b>My NOTICE</b> [$errno] $errstr<br />n";
          break;
  default:
   echo "Unknown error type: [$errno] $errstr<br />n";
         break;
 }
 /* Don't execute PHP internal error handler */
    return true; // no return (=null) is treated as true
}
//set error handler for E_USER_WARNING type only
$prevErrHandler = set_error_handler("customError"); // 2nd param can be E_USER_WARNING,..
$test = 3 ;
if ($test > 1)
{
 // trigger err of type E_USER_WARNING. Above err handler(customError) comes into affect.
 trigger_error("Value must be 1 or below", E_USER_NOTICE); // E_USER_WARNING / E_USER_ERROR / E_USER_NOTICE. Giving Error type is optional.
}
// Restore default err handler - user defined or built-in
restore_error_handler();
if ($test > 1)
{
 // this same code as above will not use 'customError' handler now.
 trigger_error("Value must be 2 or below", E_USER_WARNING);
}
/* E_USER_ERROR / E_USER_WARNING  / E_USER_NOTICE.
E_USER_ERROR will halt exectution. */
?>