Error with `tsc` when deploying functions after `create-react-app`

### [REQUIRED] Environment info

**firebase-tools:** 8.6.0

**typescript:** 3.9.7

**node:** 14.6.0

**Platform:** macOS

### [REQUIRED] Test case

Initialize a React App, then use the firebase CLI to initialize `functions` within that directory.

### [REQUIRED] Steps to reproduce

`npx create-react-app my-app --typescript`
`cd my-app`
`firebase init` - choose to initialize `functions`
`cd functions`
Add some generic code in the default boilerplate function so there are no unused imports.
`npm run deploy`

### [REQUIRED] Expected behavior

I expected the default setup and initialization would be error free. The deploy script should run without errors, particularly `tsc`.

### [REQUIRED] Actual behavior

When the script runs `tsc`, it reports errors in `../node_modules/**`, which is part of the parent dir with the React App. We see this even with a barebones setup with `npx create-react-app`, `firebase init`, and the latest version of `typescript`.