Correct exception to throw for an unhandled switch case for an argument?

Question

NOTE: This is different than the proposed duplicates as this deals with an argument rather than a value. The behavior and applicable scenarios are essentially different.

Answer 1

Since you have the login in a function you can throw InvalidArgumentException.

The exception that is raised when a parameter that is not valid is passed to a method on the referenced connection to the server.

EDIT: A better alternative would be: ArgumentException, since InvalidArgumentException in Microsoft.SqlServer.Management.Common namespace. Something like:

throw new ArgumentException("Unhandled value: " + value.ToString());