restic: restic prune: `Fatal: index is not complete`

Output of restic version

restic 0.14.0-dev (compiled manually) compiled with go1.18 on linux/amd64

How did you run restic exactly?

$ restic --cacert /path/to/file.pem -v prune --max-unused 0
repository f72c6108 opened (version 2, compression level auto)
loading indexes...
loading all snapshots...
finding data that is still in use for 18 snapshots
[11:26] 100.00%  18 / 18 snapshots
searching used packs...
{<data/[null]> <data/00000000>} not found in the index

Integrity check failed: Data seems to be missing.
Will not start prune to prevent (additional) data loss!
Please report this error (along with the output of the 'prune' run) at
https://github.com/restic/restic/issues/new/choose
Fatal: index is not complete

Environment variables:

RESTIC_REPOSITORY=s3:https://<redacted>
RESTIC_PASSWORD=<redacted>
AWS_ACCESS_KEY_ID=<redacted>
AWS_SECRET_ACCESS_KEY=<redacted>

What backend/server/service did you use to store the repository?

S3

Expected behavior

prune finishes successfully

Actual behavior

prune aborts with an error

Steps to reproduce the behavior

As of now, I’m not aware on how to consistently reproduce this issue.

Do you have any idea what may have caused this?

Previously, a backup run was terminated by the oom killer because the machine went out of RAM.

Do you have an idea how to solve the issue?

There are similiar bug reports for this kind of issue, but I’m not sure if the described solutions (e.g. remove affected snapshot) apply here as well - hence this issue. 😃

Did restic help you today? Did it make you happy in any way?

restic is just awesome 🥳