The method rhealpix_grid_as_geodataframe does not work for some resolutions

[rbejar]

It does not work for idx=5 and other resolutions (see DataTestsSpec.test_generate_rhealpix_grid). This appears to be due to some vertices from some cells falling out of the rhealpix "image". I am not sure where the problem is: some vertices of some cells in rHEALPix are actually outside of those cells. But the vertices operation in the Cell class, should take/is taking that into account? Is other thing?

The test avoids the problem but preventing the rhealpix library from doing some checks, but there should be a better solution (or at least we should be sure that we are creating the whole grid without errors).