Volumes with null entries produce unclear error

[hedss]

The following:

volumes:
    myvolume: null

Produces the error:

ValidationError: data/volumes/db-data should be object,null

This is unclear, as it suggests that the volume may be an object or a null value due to the comma, when in fact it is saying it may only be an object, followed by a comma and then what it has been set to.

[MBerka]

I thought so too, but it is actually saying exactly what hedss thought. It can be an object or null. The real confusion is that the text "null" does not get interpreted as a null value here, regardless of what my yml linter says. Here are some volumes,

volumes:
    db-data:
    mosq-conf: {}
    mosq-gen: null

and the resulting error is: data/volumes/mosq-gen should be object,null, meaning, that the blank line was interpreted as null, the braces as an object, and the "null" probably as a string (strict type checking!). The top way that this could be improved would be to add the type that failed to match the list.
"should be object,null, is a string". Not sure that the code that prints this message is in this repo though.