S126 — "If ... ElseIf" constructs should end with "Else" clauses

Why is this an issue?

This rule applies whenever an If statement is followed by one or more ElseIf statements; the final ElseIf should be followed by an Else statement.

The requirement for a final Else statement is defensive programming.

The Else statement should either take appropriate action or contain a suitable comment as to why no action is taken. This is consistent with the requirement to have a final Case Else clause in a Select Case statement.

Noncompliant code example

If x = 0 Then
    DoSomething()
ElseIf x = 1 Then
    DoSomethingElse()
End If

Compliant solution

If x = 0 Then
    DoSomething()
ElseIf x = 1 Then
    DoSomethingElse()
Else
    Throw New ArgumentException("...")
End If

Exceptions

None