[BUG] adjust bound req, for emb field padding

[m13ammed]

I suggest adjusting
pad_values mehod

into
assert bounds is not None or (already_padded and not value.shape.is_non_uniform), f"{type(self)}.pad() requires 'bounds' argument"
this prevents diffusion step (and make incompressible) for padded fields
since during diffusion step the bounds are not auto passed (at least when already_padded = True) and the pad method does not need bounds if it is already padded

[holl-]

Hi, thanks for pointing that out!
I think we should pass the bounds argument in the diffusion since it is necessary for evaluating the boundary conditions. Do you have a snippet that reproduces the error?