cue cmd hides errors in comprehensions

[mxey]

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

$ cue version
cue version v0.10.1

go version go1.23.2
      -buildmode exe
       -compiler gc
       -trimpath true
     CGO_ENABLED 0
          GOARCH arm64
            GOOS darwin
         GOARM64 v8.0
cue.lang.version v0.10.1

Does this issue reproduce with the latest stable release?

v0.10.1 is the latest stable.

What did you do?

run this testscript:

! exec cue cmd print1
! exec cue cmd print2

-- foo_tool.cue --
package foo

import (
	"tool/cli"
)

instances: {}
missingInstanceName: string

command: print1: task: {
	for _, t in instances[missingInstanceName] {
		(t): cli.Print & {text: t}
	}
}

command: print2: task: {
	for _, t in instances["foo"] {
		(t): cli.Print & {text: t}
	}
}

What did you expect to see?

PASS

I would have expected to receive errors for these two loops, because they do nonsensical lookups. Instead, CUE just “skips” them.

In other locations, the same lookups would lead to error messages, just not in the comprehension header.

What did you see instead?

unexpected command success