The Pega Product is not like an Oracle database, where you might see ORA0001, ORA0002, etc. Pega error messages tend not to use codes. We will display a message, and those messages are infinitely customizable through the use of Field Values. In addition, you can always throw an exception (which would be in the nature of an unanticipated error), and so you might see in the log "NullPointerException", which can be caused by hundreds of different possibilities, many of which could be of your own making.
Now some Frameworks use reason codes, but that is more the nature of the Framework (e.g., MasterCard has a lengthy, lengthy list of reason codes).
So not only is the answer "there is no list", but the question itself does not align at all with any of the Pega Products.