Upgrade to ESLint 9

dist/config/index.d.ts

@@ -0,0 +1,44 @@
+import type { FlatESLintConfig } from '@aet/eslint-define-config';
+import type { Linter } from 'eslint';
+
+type MiddlewareResult = Linter.Config | Linter.Config[];
+
+export type Middleware =
+  | (() => Promise<MiddlewareResult>)
+  | (() => Promise<{ default: MiddlewareResult }>);
+
+/**
+ * Returns a ESLint config object.
+ *
+ * By default, it includes `["@typescript-eslint", "import-x", "prettier", "unicorn"]` configs.
+ * Additional bundled plugins include:
+ *
+ * 1. [`react`](https://github.com/jsx-eslint/eslint-plugin-react#list-of-supported-rules)
+ *    (automatically enables
+ *    [`react-hooks`](https://github.com/facebook/react/tree/main/packages/eslint-plugin-react-hooks))
+ * 2. [`react-refresh`](https://github.com/ArnaudBarre/eslint-plugin-react-refresh)
+ * 3. [`jsx-a11y`](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y#supported-rules)
+ * 4. [`unicorn`](https://github.com/sindresorhus/eslint-plugin-unicorn#rules)
+ * 5. [`n`](https://github.com/eslint-community/eslint-plugin-n#-rules) (Node.js specific,
+ *    requires `minimatch`)
+ * 6. [`jsdoc`](https://github.com/gajus/eslint-plugin-jsdoc#rules)
+ *
+ * Non bundled:
+ * 1. [`graphql`](https://the-guild.dev/graphql/eslint/rules)
+ *
+ * @param of Configuration options.
+ * @returns ESLint configuration object.
+ */
+export function extendConfig({
+  auto,
+  middlewares: addMiddlewares,
+  configs,
+}: {
+  auto?: boolean;
+  middlewares?: Middleware[];
+  configs: FlatESLintConfig[];
+}): Promise<FlatESLintConfig[]>;
+
+export const error = 'error';
+export const warn = 'warn';
+export const off = 'off';