Exception strategy...

All untrapped error messages need to go through the log so they get
transmitted to the client

Exceptions that originate from an Action do not require a stack trace.

Exception that arise due to invalid user input do not require a stack
trace.

Exceptions that are not expected (db, network, file system) do require
a stack trace.

If the log level is debug, then all errors should be recorded with a
stack trace.

Data validation strategy...

Actions should validate as much as possible during construction.

The Repository should validate arguments.

The Database & collaborators may not validate arguments.