`mime@2` was upgrade to in https://github.com/documentationjs/documentation/pull/1003 and subsequently released in 5.4.0. Since documentation indicates that it supports [node >= 4](https://github.com/documentationjs/documentation/blob/99f4236029b3248888a7ab4f609846271ea73901/package.json#L130) and [mime@2.2.0 requires node >= 6](https://github.com/broofa/node-mime/blob/797e9cee7ac45dfa6bdc8dbe7bc396a1e6f6c581/package.json#L8) this was a breaking change.