search index push error handling is incomplete

[raboof]

when pushing objects into the search index in src/elastic.rs, the index may return a 'successful' response with errors in the response body:

{"errors": Bool(true), "items": Array([Object({"index": Object({"_id": String("MrxfoJYBymV7qHX0Jb2-"), "_index": String("42-nixos-test2"), "error": Object({"caused_by": Object({"reason": String("Can't get text on a START_OBJECT at 1:1221"), "type": String("illegal_state_exception")}), "reason": String("failed to parse field [package_teams.members] of type [keyword] in document with id 'MrxfoJYBymV7qHX0Jb2-'. Preview of field's value: '{github=globin, name=Robin Gloster, email=mail@glob.in}'"), "type": String("mapper_parsing_exception")}), "status": Number(400)})})]), "took": Number(5)}

See also the examples in https://docs.rs/elasticsearch/latest/elasticsearch/