herr_t represents failure when <= 0, but gADIOS2ReadVar considers == 0 success.

[vicentebolea]

A note for the future: according to hdf5 docs: https://docs.hdfgroup.org/hdf5/develop/_h5public_8h.html#title52 . A herr_t represents failure when <= 0, but gADIOS2ReadVar considers == 0 success. No something to change in this MR, but it will be good to address it in the future either getting rid of using herr_t in our codebase or following the hdf5 usage of it.

Originally posted by @vicentebolea in https://github.com/ornladios/ADIOS2/pull/3516#discussion_r1123376867