Checking for null ...coming null....no reaction but crash

try
{
    if(ringValue.data instanceof Toybox.Lang.Float)
    {
        ringArray[i] = ringValue.data.toNumber();
     }
}catch(ex)
{}
I m sorry to say that, I debugged this ringValue.data has been null and CCCCRASH...the what..
the same action with checking explizit if(ringValue.data == null) coming null...not jump but crash.
..the what please!!!