! exec cue export x.cue
stderr 'invalid module file .*module\.cue: empty module path'
-- cue.mod/module.cue --
module: ""
language: version: "v0.8.0"
-- x.cue --
a: 1
-- _registry/example.com_v0.0.1/cue.mod/module.cue --
module: "example.com@v0"
language: version: "v0.8.0"

-- _registry/example.com_v0.0.1/top.cue --
package main
