Fix not restoring error handler
Fix not restoring error handler

By overwriting the error handler there would be an infinite loop of exceptions, one should always try to restore the error handler. This is just an example of how it should be done througout the project.

Note: one can also use `finally` if PHP >=5.5.
revinate/php-amqplib,eexit/php-amqplib,postalservice14/php-amqplib,php-amqplib/php-amqplib,videlalvaro/php-amqplib