eslint-plugin/configs/recommended.js // ensure that typescript type c…

…hecker is executed.

eslint/no-unused-vars got disabled when introducing support for TypeScript with WordPress#27143 (2-3 years ago) when Gutenberg was moving to Typescript. By disabling this feature, the Typescript type checker will not be executed. We actively enable "no-unused-vars" and "@typescript-eslint/no-unused-vars" and additionally setting "ignoreRestSiblings" to "true", which is actively used in Gutenberg.

See more information in: WordPress#54305

packages/eslint-plugin/configs/recommended.js

@@ -55,8 +55,12 @@ if ( isPackageInstalled( 'typescript' ) ) {
 				// Don't require redundant JSDoc types in TypeScript files.
 				'jsdoc/require-param-type': 'off',
 				'jsdoc/require-returns-type': 'off',
-				// Handled by TS itself.
-				'no-unused-vars': 'off',
+				// Setting "no-unused-vars" to "off" will also disable
+				// the typescript type checker. So we need to explicitly enable it,
+				// but want to ignore "unused rest siblings".
+				// @issue https://github.com/WordPress/gutenberg/issues/54305
+				'no-unused-vars': [ 'error', { ignoreRestSiblings: true } ],
+				'@typescript-eslint/no-unused-vars': [ 'error', { ignoreRestSiblings: true } ],
 				// no-shadow doesn't work correctly in TS, so let's use a TS-dedicated version instead.
 				'no-shadow': 'off',
 				'@typescript-eslint/no-shadow': 'error',