jit.cellblock empty values

Hi,

Is there any way to detect empty values in cellblock? So if cell 1,1 is empty it outputs a 0 or at least something I can detect that its empty?

For instance, Im going through each cell and then using zl slice 2 to clip the value of the cell, but when it is empty it just outputs nothing at all. It just misses out this part of the iteration.