ecCodes 'field->file' assertion fails on index.select()

[acowlikeobject]

I'm running into a peculiar problem where I can build, write and select from index files once, but if I do it again in the same interpreter session, I get an ecCodes assertion failed.

E.g., in the following snippet, I run exactly the same lines twice; it works the first time but crashes the second. So far I'm able to reproduce this with any grib I use.

Am I not using index objects correctly? Or is something else going on?

import pygrib

grib_path = 'test.grib'

for idx_path in (grib_path + '.idx1', grib_path + '.idx2'):
    index = pygrib.index(grib_path, 'endStep')
    index.write(idx_path)
    index.close()

    pygrib.index(idx_path).select(endStep=0)  # Test  open and select.
    print(idx_path, 'worked')

Output:

test.grib.idx1 worked                                                                                                                                                                               
ecCodes assertion failed: `field->file' in /home/conda/feedstock_root/build_artifacts/eccodes_1579074340882/work/src/grib_index.c:1470
Aborted (core dumped)

[acowlikeobject]

Actually, this issue is entirely within eccodes. Opened an issue there.