I get this error
[OutOfRangeException] Offset out of range
Though I have used
set_error_handler(array($this, 'handleError'));
in constructor. But the code flow never comes to handleError method and program exits after the error.
PHP's set_error_handler sets a handler for Errors, not Exceptions.
In user code, errors can be triggered with trigger_error, while exception can be thrown with throw. The standard library uses a mix of these techniques.
The code you are using is throwing an exception, to stop that ending your program, you need to wrap it in a try..catch construct.