[TOGoS]

> Hand-waving away making breaking changes to an API because "people don't care" about handling the error conditions

Generally, adding more specific exception types, so long as they are subclasses of exception types already handled, would not be a breaking API change. Your general exception handler would still run, and you could choose to do something special with the new exceptions if that helps your calling program be better.

Changing how a certain error case is represented such that a previously triggered handler is no longer triggered might be considered breaking, though.