If not defined, etc., it will not be recognized.

main.js
```
var some = {};
module.exports = some;

a
```

errorCheck.js
```
var file = require("path").join("main.js");
var src = require("fs").readFileSync(file);
var ec = check(src, file);

if(ec) return { ... };
require("./main.js");
...
```

```
uncaughtException - a is not defined
```