Coping with missing field

[hansbogert]

I have the following situation:

foo: fieldA: {bar: "1"}
foo: fieldAB: {bar: "1"}

foo: A = [N = =~".*[^B]"]: {
        _musthaveaB: foo["\(N)B"].bar == A.bar & true
}

This works fine. Changing the second line to:

foo: fieldAB: {bar: "2"}

Results in:

 cue vet foo.cue
foo.fieldA._musthaveaB: conflicting values true and false:
    ./foo.cue:4:24
    ./foo.cue:5:15
    ./foo.cue:5:41

Still as expected.

However, if we comment out the second line, cue vet succeeds.

I thought the unification with true was pretty elegant in my case, but only after a while noticed this false positive.

What would be the idiomatic way to check that every field not ending in "B", should have a ...B counterpart with the same value?

The above behaviour with a missing but expected field not showing an error after vet or evaluation has been the biggest gotcha with Cue so far.