Error creating product subset using Subset operator

Sounds reasonable to consider negative width and height, even this is not a frequent use case. But I guess, it is easy to implement. So, we can support it.

@Marco Peters I have an other approach to solve this problem to consist of use (only in multisize subset) geometry region computing with geocoding option computed at border pixel (not use center pixel) .
In fact, the region intersection under pixel ( for smaller band) provide null intersection because the geocoding is computed at the center.
I have implemented a workaround on new fix branch SNAP -1301 (not avaible for moment, soon).

@Marco Peters There is an other problem closed to SNAP-1301 issue:
the UI authorize ROI with negative width (if i choose start x at 100 and end x at 50 , the resulting width is -50). I can change it following the same issue, what do you think?

The issue is due to small band (smaller than selected region and present less 1 pixel surface according with reference selection example 30x30) like sun azimut in Sentinel 2 product. This kinds of bands are too smalls or outside the selection to be subset. A local resampling is needed before to avoid area region is null.

It is possible to workaround this problem by first resampling the product to one common resolution and then doing the subset.

A report in the forum: https://forum.step.esa.int/t/minimum-size-for-a-subset/24346