Iternal change of not assuming the error `code` property exists, as on certain node versions its existance is denied. This should fix the following error:

```
./node_modules/editions/edition-node-0.8/index.js:310
      if (editionError.code.indexOf('unsupported-edition-engines-node-version') === 0) {
                           ^

TypeError: Cannot read property 'indexOf' of undefined
```