[Bug]: Useless warnings are printed when using pull API

[jonasseglare]

What version of Datahike are you using?

0.7.1663

What version of Java are you using?

Java(TM) SE Runtime Environment Oracle GraalVM 25+37.1 (build 25+37-LTS-jvmci-b01)

What operating system are you using?

MacOS

What database EDN configuration are you using?

{:attribute-refs? true,
:index :datahike.index/persistent-set,
:keep-history true,
:name "jobtech-taxonomy-db",
:schema-flexibility :write,
:store {:backend :memory
:id #uuid "7dc50266-5d1c-beef-a6f8-badcafe10113"}}

Describe the bug

When using the pull API, e.g.

                     (dc/q '[:find (pull ?edge [:db/id
                                                :mapping.edge/source
                                                :mapping.edge/target
                                                :mapping.edge/mapping])
                             :keys edge
                             :in $ [[?source ?target] ...]
                             :where
                             [?edge :mapping.edge/source ?source]
                             [?edge :mapping.edge/target ?target]]
                           db source-id+target-id-set)

lots of warnings are printed. The warnings come from the function datahike.pull-api/db-ident-and-id which in turn indirectly calls the function datahike.db.interface/-ident-for. The function datahike.pull-api/db-ident-and-id is clearly written in such a way that it expects the ident to sometimes be nil, but datahike.db.interface/-ident-for will always warn if it returns nil even if that nil is expected.

As a consequence, the call to the pull API tends to result in a lot of false-alarm warnings being spammed, e.g.

2026-03-31T13:16:48.081731Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 167540}
2026-03-31T13:16:48.081953Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 103119}
2026-03-31T13:16:48.082024Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 234739}
2026-03-31T13:16:48.082070Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 236291}
2026-03-31T13:16:48.082151Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 100736}
2026-03-31T13:16:48.082198Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 16770}
2026-03-31T13:16:48.082244Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 226485}
2026-03-31T13:16:48.082277Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 234739}
2026-03-31T13:16:48.082309Z :warn datahike.db :datahike/attribute-ref-not-found 
  data: {:ref 236291}

What is the expected behaviour?

No warnings from using the pull API.

How can the behaviour be reproduced?

Check out this commit: https://gitlab.com/arbetsformedlingen/taxonomy-dev/backend/jobtech-taxonomy-api/-/tree/0fef5f60899aadbf351b798cda6199e0a74c0100

and run clj -M:dev -m dev from the terminal, and you will see the warnings.