Incorrect MSRG bounding boxes at UTM zone boundaries?

[gregsadetsky]

Bounding boxes for MSRG 100km grid zones near UTM zone boundaries seem incorrect.

For instance, calling USNGtoLL with the grid zone identifiers 16RGV and 17RKQ returns bboxes which overlap.

Visual demonstration:
https://gregsadetsky.github.io/mgrs-usng-js-libs-overlap/demonstrations/codice-usng/dist/

• the red (overlapping) polygons' coordinates are generated using USNGtoLL
• the green (non-overlapping) polygons are coming from the reference 16R / 17R shapefiles from the NGA.

Demonstration code:
https://github.com/gregsadetsky/mgrs-usng-js-libs-overlap/blob/master/demonstrations/codice-usng/app.js