ABAP: "IF ... ELSEIF" constructs should end with "ELSE" clauses

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 OTHERS clause in a CASE
statement.

Noncompliant Code Example

IF RESULT > 0.
  PERFORM do_something.
ELSEIF RESULT = 0.
  PERFORM do_something_else.
ENDIF.

Compliant Solution

IF RESULT > 0.
  PERFORM do_something.
ELSEIF RESULT = 0.
  PERFORM do_something_else.
ELSE.
  PERFORM error.
ENDIF.