Return null rather than {} when mimos.type() finds no match

[devinivy]

Support plan

• is this issue currently blocking your project? (yes/no): no
• is this issue affecting a production system? (yes/no): no

Context

• node version: v12+
• module version: v5/v6
• environment (e.g. node, browser, native): node
• used with (e.g. hapi application, another framework, standalone, ...): hapi
• any other relevant information: This would be a breaking change that would propagate to hapi's API 🚨 , since hapi exposes an instance of mimos through server.mime.

What problem are you trying to solve?

The interface of the Mimos instance can be awkward to work with (particularly with typescript) because mimos.type() returns an empty object {} when there is no mime type match, and an object with some properties when there is a match.

Do you have a new or modified API suggestion to solve the problem?

The proposal from #37 is for mimos.path() to return null when there is no mime type match.

[kanongil]

FYI, I'm not sure the enhanced ergonomics is worth the potential issues this can create with old code, as per #37 (comment).

[devinivy]

I'm comfortable with that 👍