bool = pfontmap:IsNull()
True if the fontmap is NULL, i.e. invalid. If functions
that allocate fontmaps fail, they might not throw an error but simply set the
fontmap to NULL. You can use this function to check if fontmap allocation has
failed in which case the fontmap 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 fontmap is NULL, otherwise False