"It looks to me more like an underlyingly empty position that in the
right circumstances may be filled by default with a prothetic glide. Its
most common habitat is a syllable lacking a consonantal onset, and the
usual slot-filler is either a glide homorganic with whatever follows
(e.g. [j]/[w] before front/back vowels, or a glottal onset -- [h] or
[?]). It isn't really a phonological zero, since it has a predictable
surface realisation." Piotr, GASIOROWSKI, POLAND
Oh, yes, the homorganic glide is another realization of the null phoneme
/Ø/.