No exports found when there's only export * from ...

My config for this rule is

```
'import-x/no-unused-modules': [
  'error',
  {
    missingExports: true
  }
]
```

I get `No exports found  import-x/no-unused-modules` if a file contains only `export * from ...` without any named exports.

Is it a bug or a feature?