lint: enable eslint-plugin-unicorn rules #4369

Also allows removal of the "no-null" package, which is not maintained
(and the unicorn version better by avoiding false positives).

Author: justinmk3

.eslintrc.js

@@ -2,14 +2,17 @@ module.exports = {
     root: true,
     parser: '@typescript-eslint/parser',
     parserOptions: {
+        ecmaVersion: 'latest',
+        sourceType: 'module',
         project: './tsconfig.json',
         tsconfigRootDir: __dirname,
     },
     env: {
         node: true,
         mocha: true,
+        es2024: true,
     },
-    plugins: ['@typescript-eslint', 'header', 'no-null', 'aws-toolkits'],
+    plugins: ['@typescript-eslint', 'unicorn', 'header', 'aws-toolkits'],
     extends: [
         'eslint:recommended',
         'plugin:@typescript-eslint/eslint-recommended',
@@ -90,7 +93,6 @@ module.exports = {
         '@typescript-eslint/no-namespace': 'error',
         // This is off because prettier takes care of it
         'no-extra-semi': 'off',
-        'no-null/no-null': 'error',
         '@typescript-eslint/no-empty-function': 'off',
         '@typescript-eslint/no-unused-vars': 'off',
         '@typescript-eslint/no-floating-promises': 'error', // Promises must catch errors or be awaited.
@@ -105,6 +107,39 @@ module.exports = {
         // Do not check loops so while(true) works. Potentially reevalute this.
         'no-constant-condition': ['error', { checkLoops: false }],
         'no-empty': 'off',
+
+        // Rules from https://github.com/sindresorhus/eslint-plugin-unicorn
+        // TODO: 'unicorn/no-useless-promise-resolve-reject': 'error',
+        // TODO: 'unicorn/prefer-at': 'error',
+        // TODO: 'unicorn/prefer-event-target': 'error',
+        // TODO: 'unicorn/prefer-negative-index': 'error',
+        // TODO: 'unicorn/prefer-string-slice': 'error',
+        // TODO: 'unicorn/prefer-regexp-test': 'error',
+        // TODO: 'unicorn/prefer-ternary': 'error',
+        // TODO(?): 'unicorn/custom-error-definition': 'error',
+        // TODO(?): 'unicorn/prefer-json-parse-buffer': 'error',
+        // TODO: ESM modules https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-module.md
+        // 'unicorn/prefer-module': 'error',
+        'unicorn/no-abusive-eslint-disable': 'error',
+        'unicorn/no-null': 'error',
+        'unicorn/no-unnecessary-polyfills': 'error',
+        'unicorn/no-useless-spread': 'error',
+        'unicorn/prefer-array-some': 'error',
+        'unicorn/prefer-blob-reading-methods': 'error',
+        'unicorn/prefer-code-point': 'error',
+        'unicorn/prefer-date-now': 'error',
+        'unicorn/prefer-dom-node-text-content': 'error',
+        'unicorn/prefer-includes': 'error',
+        'unicorn/prefer-keyboard-event-key': 'error',
+        'unicorn/prefer-modern-dom-apis': 'error',
+        'unicorn/prefer-modern-math-apis': 'error',
+        'unicorn/prefer-native-coercion-functions': 'error',
+        // 'unicorn/prefer-node-protocol': 'error',
+        // 'unicorn/prefer-object-from-entries': 'error',
+        'unicorn/prefer-reflect-apply': 'error',
+        'unicorn/prefer-string-trim-start-end': 'error',
+        'unicorn/prefer-type-error': 'error',
+
         'header/header': [
             'error',
             'block',