inner_hits empty if null objects exist in path

[abulhol]

I use top level inner hits to retrieve data from multiple nested documents.
Elasticsearch returns empty inner hits arrays for some of the hits, which is probably due to the existence of null objects inside the nested documents.
Please see a detailed description of the problem in this forum entry:
https://discuss.elastic.co/t/nested-query-missing-inner-hits/41038
I have looked at these documents with jq like this:
jq .a.b.c.d.first[].e.f.second[].message<json>
and the output is e.g. like this:

"Some message"
"Some other message"
jq: error: Cannot iterate over null

So I believe Elasticsearch iterates over the nested documents in a similar way and returns null if any of the nested objects is null (?).
I guess the ES code needs to be fixed then?

[abulhol]

I found out that this is not really the reason for my problem, see the update in the forum issue I wrote. It has to do with the complex syntax for inner hits that I did not fully understand.
See also:
#13064
and this one:
#16143 (comment)