TypeError: Cannot read property 'properties' of undefined

While running `npm run build` I got the following error

```
describe: optionsSchema.definitions.output.properties.path.description,

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

As suggested here [1], bumping the `webpack-cli` to **3.1.1** solved my issue.

[1] https://github.com/webpack/webpack-cli/issues/607

Start by running `npm run build` to reproduce the `optionsSchema.definitions.output.properties` error, then inspect the project's dependency declaration for `webpack-cli`. Update it to version 3.1.1 as indicated by the issue, rerun the build, and consider the issue done when the command completes without this TypeError.

Written by the indexing model from the issue text.