SA0090: POUs should have a only one exit point

Function	Detects code positions where the RETURN statement is not the last statement in a function, method, property or program. It also recognizes places where there is a RETURN within an IF branch.
Reason	A RETURN in the code leads to poorer maintainability, testability and readability of the code. A RETURN in the code is easily overlooked. You must insert code, which should be executed in any case when a function exits, before each RETURN. This is often overlooked.
Importance	Medium
PLCopen rule	CP14

Sample:

FUNCTION F_TestFunction : DINT
VAR_INPUT
    bTest   : BOOL;
END_VAR

IF bTest THEN
    RETURN;                      // => SA0090
END_IF
 
F_TestFunction := 99;