OIC javascript issue

Summary:

I have a javascript that parses JSON input and returns a value for a particular tag. When the tag is missing from the payload it used to return 'undefined' till recently but now I am getting error —> fault name mappings for exception: BPEL_SELECTION_FAILURE

original function:

function getAssetRetiredPeriod(input)
{
var temp=JSON.parse(input);
var output=temp.X_PERIOD_CTR_FULLY_RETIRED;
return output;
}

I am trying to modify it handle the missing tag but below function is not valid in OIC. Not sure what I am doing wrong. Are there any limitations on javascripts in OIC?

function getAssetRetiredPeriod(input)