feat: add prefer-optional-chain

Author: felixfbecker

.eslintrc.js

@@ -240,8 +240,11 @@ module.exports = {
         '@typescript-eslint/prefer-function-type': 'error',
         '@typescript-eslint/prefer-includes': 'error',
         '@typescript-eslint/prefer-namespace-keyword': 'error',
+        '@typescript-eslint/prefer-optional-chain': 'error',
+        '@typescript-eslint/prefer-nullish-coalescing': 'off', // https://github.com/typescript-eslint/typescript-eslint/issues/1265
         '@typescript-eslint/type-annotation-spacing': 'off',
         '@typescript-eslint/triple-slash-reference': 'error',
+        '@typescript-eslint/return-await': 'error',
         '@typescript-eslint/unbound-method': 'error',
         '@typescript-eslint/unified-signatures': 'error',