Symfony version(s) affected: 4.3

Description
The RedeliveryStamp, used for handling retrying of messages, requires in the constructor the $senderClassOrAlias argument.
However, in the Worker.php class, on line 148, a new instance of the object is created, and the $senderClassOrAlias argument can be null according to the code there, so the application crashes when trying to handle a message whose handler returned an error.

How to reproduce
Publish a message to a queue. Try to handle that message but return an exception in the handler. Notice the exception.

Possible Solution
Allow $senderClassOrAlias argument to be null.