calling intersection between two MooseQueryResult produces an error because "MooseQueryResult
is not a variable type"

This is raised in basicNew:

A possible workaround is to redefine MooseQueryResult>>intersection: aCollection
    | result |

    result := self class new.

    aCollection do: [ :each|
        ((self includes: each) and: [(result includes: each) not])
                ifTrue: [ result add: each]].

    ^ result

But it might not be the best solution since I assume basicNew: might be called from
other methods ...