Strange behavior of // operator since 4.45.3

[lbilger]

Describe the bug
It seems that the behavior of the // operator has changed between 4.45.2 and 4.45.3. I have been wondering why my expression failed with the newer version (I upgraded from 4.45.1 to 4.45.4) and tried around a lot. This is what I found.

Version of yq: 4.45.3 and 4.45.4
Operating system: Mac
Installed via: brew and docker

Input Yaml
data.yml

- foo: false

Command
The command you ran:

yq -o json  '.[] | (select(.foo) | {"foo": .foo} // {})' data.yml

Actual behavior

no output

Expected behavior

{}

Additional context
I wrote the following script to test this on multiple versions easily:

#!/usr/bin/env bash

test_data='
- foo: false
'

for version in 4.45.1 4.45.2 4.45.3; do
  for command in '.[] | (select(.foo) | {"foo": .foo} // {})' '.[] | (select(.foo) | {.foo} // {})'; do
    echo ${version} "${command}"
    echo -------
    echo "${test_data}" | podman run -i --rm  mikefarah/yq:${version} -o json "${command}"
    echo -------
    echo
  done
done

Note that '.[] | (select(.foo) | {.foo} // {})' yields a result in all versions, but '.[] | (select(.foo) | {"foo": .foo} // {})' doesn't in versions 4.45.3 onwards.