Are there situations where you can NOT override the FA_errno's code?

I have a script that does the following:

1. creates an array
2. calls a function that populates the array with a list of paragraphs in the FrameMaker document
3. executes a while loop that then process this array. The while loops conditional is FA_errno==Constants.FE_Success.

The function returns a FA_errno of -3, which is fine because I was using the ObjectValid method to iterate through the paragraphs so eventually the object will be invalid. My problem is that I cannot override the error code after I exit that funciton. The FA_errno stays set to negative 3. Am I missing something or are there situations that forbid you from overriding the error code?

The relevant code is as follows:

var vDoc=app.ActiveDoc;

var vFlowArray=new Array();

var vFirstPgf=vDoc.MainFlowInDoc.FirstTextFrameInFlow.FirstPgf;

getPgfList (vFirstPgf, vFlowArray);

//due to getPgfList function, the FA_errno is -3 so i am going to overwrite the code

FA_errno=Constants.FE_Success

while (FA_errno==Constants.FE_Success)

//a bunch of stuff occurs in the while condition but i am not showing it because this never evaluates to true

function getPgfList (pPgf,pArray)

{

    while (pPgf.ObjectValid())

    {

        pArray.push (pPgf);

        pPgf=pPgf.NextPgfInFlow;

        }

         }