Check "extra" exceptions

[jskeet]

We're not convinced that the list in 21.5 is complete

Examples:

• InvalidOperationException when using .Value
• SwitchExpressionException for unhandled switch arms

[jnm2]

(SwitchExpressionException is thrown if it is found at compile time, otherwise InvalidOperationException (its base class) is thrown.)

[jskeet]

Keep in this milestone, but not block the release on it.