chore(deps): upgrade to typescript-eslint v4 (#129)

BREAKING CHANGE: Update `@typescript-eslint/eslint-plugin` to `^4.0.1`

README.md

@@ -14,7 +14,7 @@ npm install eslint-config-airbnb-typescript \
             eslint-plugin-jsx-a11y@^6.3.1 \
             eslint-plugin-react@^7.20.3 \
             eslint-plugin-react-hooks@^4.0.8 \
-            @typescript-eslint/eslint-plugin@^3.6.1 \
+            @typescript-eslint/eslint-plugin@^4.0.1 \
             --save-dev
 ```
 
@@ -42,7 +42,7 @@ Install dependencies. ESLint plugins [must also be installed](https://github.com
 ```bash
 npm install eslint-config-airbnb-typescript \
             eslint-plugin-import@^2.22.0 \
-            @typescript-eslint/eslint-plugin@^3.6.1 \
+            @typescript-eslint/eslint-plugin@^4.0.1 \
             --save-dev
 ```
 

lib/shared.js

@@ -115,6 +115,16 @@ module.exports = {
     'no-magic-numbers': 'off',
     '@typescript-eslint/no-magic-numbers': baseBestPracticesRules['no-magic-numbers'],
 
+    // Replace Airbnb 'no-redeclare' rule with '@typescript-eslint' version
+    // https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-redeclare.md
+    'no-redeclare': 'off',
+    '@typescript-eslint/no-redeclare': baseBestPracticesRules['no-redeclare'],
+
+    // Replace Airbnb 'no-shadow' rule with '@typescript-eslint' version
+    // https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-shadow.md
+    'no-shadow': 'off',
+    '@typescript-eslint/no-shadow': baseVariablesRules['no-shadow'],
+
     // Replace Airbnb 'no-throw-literal' rule with '@typescript-eslint' version
     // https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/no-throw-literal.md
     'no-throw-literal': 'off',
@@ -183,11 +193,6 @@ module.exports = {
     {
       files: ['*.ts', '*.tsx'],
       rules: {
-        // Disable `no-undef` rule within TypeScript files because it incorrectly errors when exporting default interfaces
-        // https://github.com/iamturns/eslint-config-airbnb-typescript/issues/50
-        // This will be caught by TypeScript compiler if `strictNullChecks` (or `strict`) is enabled
-        'no-undef': 'off',
-
         /* Using TypeScript makes it safe enough to disable the checks below */
 
         // Disable ESLint-based module resolution check for improved monorepo support