Detect Missing Exports in commonjs?

I'd like to be able to detect when I'm requiring a file that has no exports. Maybe more specifically when I try to assign it to a variable. For example:

```
// y.js

function xyz() {
console.log("HELLO")
}
```

```
// x.js
const y = require('./y'); // <- this should be a lint error because y.js exports nothing

y();
```

Apologies if this is already possible and I'm just doing something wrong.

Use the x.js/y.js example in the issue as the reproducer: requiring y.js yields no exports, but assigning the result to y is not flagged. Identify the existing CommonJS import analysis and its tests, then consider the work complete when this case is detected without incorrectly flagging valid exports.

Written by the indexing model from the issue text.