What to do with these ERA reports?

So in my ERA I get these reports for example the following it says Invalid Value

Im getting a an iterator then I'm getting the next value and I do checks on the value and then set the text of a label. It gives me error invalid value on the setText part of the label.

I don't know what I could do more to check if its correct or not? I wish ERA would report the actual value that was given or something. 

var sensorIter = getIterator();

var lastvalue = sensorIter.next();

if (lastvalue != null &&
    lastvalue has :data &&
    lastvalue.data != null &&
    (lastvalue.data instanceof Number ||
    lastvalue.data instanceof Float ||
    lastvalue.data instanceof Long ||
    lastvalue.data instanceof Double)) {
          
        hpadifference.setText(lastvalue.data.toNumber().toString());
}