Librairies that wrap exceptions into something else often do a disservice to their users. In this `Prefs:save()` example, what should the wrapping library throw? A "SaveFailedException"? That's more abstract, however now I would need to go check the source code of the library, find where the exception has been converted to something else, comment out the "try/catch" statement, and rerun the program. Then I can finally now what really happened and do something to fix it.
If done right, rethrowing exceptions does not affect the ability to debug the code. You don't throw a pristine new exception on the spot. You wrap the exception in a new one, effectively maintaining all the information. Coded recoverability suffers, but debugging ability does not. You have the same debugging information in the rethrown exception as you did in the bubbled up one.
