bool = playout:IsNull()
True if the layout is NULL, i.e. invalid. If functions
that allocate layouts fail, they might not throw an error but simply set the
layout to NULL. You can use this function to check if layout allocation has
failed in which case the layout will be NULL.
Also, certain getter functions can return a NULL object in case the object
doesn't exist. You can use this function to check if a getter function returned
a NULL handle.
True if the layout is NULL, otherwise False