fix all `@typescript-eslint/no-unused-vars` warning

[xuatz]

After fixing the, we can update the rule to on (by removing it)

// packages/eslint-config/index.js
module.exports = {
  ...
  rules: {
	...
    'react/jsx-uses-react': 'off',
    'react/react-in-jsx-scope': 'off',
-    '@typescript-eslint/no-unused-vars': 'warn', // TODO fix and remove when we have bandwidth #45
    '@typescript-eslint/no-var-requires': 'warn', // TODO remove when we convert to TS fully
  },
};