Fix build for TS 4.0

[dsherret]

Looks like TypeScript renaming a property on the TupleType node broke a lot of stuff.

Waiting on facebook/create-react-app#9515 to be fixed.

[dsherret]

I should just drop create react app eventually as I don't really need it. Now waiting on these two new bugs:

• 4.0.0 breaks with typescript (all versions) facebook/create-react-app#9868
• Error when trying to run an upgraded CRA 4 Typescript project facebook/create-react-app#9874

[dsherret]

Ended up just implementing #82. create-react-app does not seem to value TypeScript support.

[ChristianIvicevic]

Offtopic banter: Just saw your issue referenced over in CRA, the mentioned fix in one of the issues, especially the comment at the end of the post is pure gold: facebook/create-react-app#9868 (comment)

Unfortunately create-react-app will most likely not consider Typescript a first-class citizen for a long time...

[dsherret]

@ChristianIvicevic that's kind of funny, but also disappointing 😐