cue/load: non-package CUE file causes resolution logic to fail

[rogpeppe]

This issue was originally raised by Judson Lester (@nyarly) in this Slack thread.

What version of CUE are you using (cue version)?

v0.9.1

Does this issue reproduce with the latest stable release?

Yes, but it's a regression since earlier.

What did you do?

exec cue vet
-- cue.mod/gen/other.example/monitoring/register_go_gen.cue --
package monitoring

-- cue.mod/module.cue --
module: "test.example"
language: version: "v0.9.0"

-- prometheus-api.cue --
package kustomize

import "other.example/monitoring"
_z: monitoring

-- unnamed.cue --
import ()

What did you expect to see?

A passing test

What did you see instead?

> exec cue vet
[stderr]
test.example@v0: import failed: no dependency found for package "other.example/monitoring":
    ./prometheus-api.cue:3:8
[exit status 1]
FAIL: /tmp/y.txtar:1: unexpected command failure