Update ESLint config (#242)

template/_eslintrc.js

@@ -1,8 +1,16 @@
 module.exports = {
   root: true,
   extends: '@react-native-community',
-  rules: {
-    "no-shadow": "off",
-    "@typescript-eslint/no-shadow": ["error"],
-  },
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint'],
+  overrides: [
+    {
+      files: ['*.ts', '*.tsx'],
+      rules: {
+        '@typescript-eslint/no-shadow': ['error'],
+        'no-shadow': 'off',
+        'no-undef': 'off',
+      },
+    },
+  ],
 };

template/package.json

@@ -20,6 +20,8 @@
     "@types/jest": "^26.0.23",
     "@types/react-native": "^0.66.4",
     "@types/react-test-renderer": "^17.0.1",
+    "@typescript-eslint/eslint-plugin": "^5.7.0",
+    "@typescript-eslint/parser": "^5.7.0",
     "babel-jest": "^26.6.3",
     "eslint": "^7.14.0",
     "jest": "^26.6.3",