Support optional properties.

[WestonThayer]

It's common for properties of Typescript interfaces to be optional:

interface Thing {
  foo: string;
  bar?: string;
}

typedPath<Thing>().bar.$path raises an Object is possibly 'undefined' error, when that's probably not desireable.

[bsalex]

Hi @WestonThayer.
Could you try the latest version?
Here is the test that is passing:

typed-path/index.spec.ts

Line 62 in 3d46b6e

expect(tp<OptionalThing>().bar.$path).to.equal('bar');

If it still doesn't work - could you clarify the version of TypeScript you are using?

[WestonThayer]

Good call, it was an issue with my Typescript version. Upgraded to latest and everything is fine.

[bsalex]

@WestonThayer
I've reproduced the problem you described with typescript in strict mode.
The issue has been fixed here: 0f6d6bb
Please check version 2.1.2