Missing and unused dependencies

When running `depcheck` in the main directory (after a `yarn global add depcheck`), there are some unused and missing dependencies reported:
```
Unused dependencies
* @types/jest
* @types/node
Missing dependencies
* eslint-config-react-app: .\package.json
* babel-eslint: .\package.json
* eslint-plugin-import: .\package.json
* eslint-plugin-flowtype: .\package.json
* eslint-plugin-jsx-a11y: .\package.json
* eslint-plugin-react: .\package.json
* eslint-plugin-react-hooks: .\package.json
* @redux-saga/core: .\src\index.tsx
```
^{(Where one of the "unused" dependencies caused some issues in another context).}

Can somebody who is more familiar with dependency management confirm that

1. the unused dependencies can safely be removed
2. it makes sense to add the missing dependencies

?

(The missing ones don't seem to be strictly necessary, that's why I'm not sure...)

Run depcheck in the repository's main directory, then inspect package.json and the reported import in src/index.tsx. Check each unused and missing dependency against the project configuration and source usage; the work is done when the dependency declarations are justified and depcheck's report is resolved or explained.

Written by the indexing model from the issue text.