hasAndBelongsToMany related array has only "null" entry when limiting fields

[technicallyfeasible]

I have a model which is related to another model (countries) through hasAndBelongsToMany. When I do a filter with include like this
{
"include": [{
"relation": "countries",
"scope": {
"fields": ["name"]
}
}]
}

then in my response I get something like this
"countries": [
null
]

and without the scope
"countries": [
{
"name": "Argentina",
"id": "54d11335123c16580c55e0c8",
"continentId": "54d11333123c16580c55e0c7"
}
]

[raymondfeng]

Please create a test project on github to reproduce the issue per https://github.com/strongloop/loopback/wiki/Issues.

[technicallyfeasible]

I created a test repository as described in the link:
https://github.com/technicallyfeasible/loopback-sandbox

Just start it and use the explorer __get__Companies with the following filter:
{"include":{"relation":"countries", "scope":{"fields":["name"]}}}

I expect the list of companies with the linked countries for each one but only the "name" property. Instead for each linked Country there is only "null" in the countries array.

[superkhau]

The inclusion filter is erroneous applied to the association table. As a result, the queries on related tables all become null. @raymondfeng has a fix in the works at loopbackio/loopback-datasource-juggler#476. Track progress on that issue instead, closing this one.