This check ensures that if a method or class method is declared to return a
value, such as in:
Method foo() As %String
{
// code here
}
then all code paths eventually either return a value of throw an
exception.
Limitations: macros
ObjectScript allows to use macros as statements. But macros are not expanded.
It is therefore the choice of the plugin user as to whether to consider macros
as violating this rule.