DoesNotExist instance error message is empty in v5 onwards

[l0b0]

After upgrading pynamodb 4.3.3 to 5.0.3, a test of the logging of a DoesNotExist error started failing. It looks like the DoesNotExist.msg instance field used to be set to the DoesNotExist.msg class field value, but that this is no longer the case: when catching a DoesNotExist error in production code the msg field is None. Is this intentional?