Well, yes and no. Of course, it's a good thing to know your subs. But I work with "objects" and one of it's properties is used as a special sub-call. But it does not need to exist.
Life would become easier (just like the function_exists in PHP for example). I'm just missing the check of existence. The controls for example. Do you put all your controls in array? I don't, but trying to set a control, because you use a template for example, which does not exist causes an error to rise. And yes to catch those errors errorlabel could be used, but I think the errorlabel thing is not what it should be. I'm not interested if an error somewhere in my sub occurs, but do if it's on a specific statement. Now I have to define a whole new sub just to catch these kind of errors......