chore: bump eslint to v9

eslint.config.js

@@ -0,0 +1,53 @@
+import eslint from "@eslint/js";
+import tseslint from "typescript-eslint";
+import stylistic from "@stylistic/eslint-plugin";
+import globals from "globals";
+
+export default tseslint.config({
+    extends: [
+        eslint.configs.recommended,
+        ...tseslint.configs.strictTypeChecked,
+        ...tseslint.configs.stylisticTypeChecked,
+        ...tseslint.configs.recommendedTypeChecked,
+        stylistic.configs.customize({
+            quotes: "double",
+            indent: 4,
+            semi: true,
+        }),
+        {
+            languageOptions: {
+                parserOptions: {
+                    project: true,
+                    tsconfigRootDir: import.meta.dirname,
+                },
+                globals: {
+                    ...globals.browser,
+                    StackExchange: "readonly"
+                },
+            },
+        },
+    ],
+    rules: {
+        "eqeqeq": "error",
+        "no-await-in-loop": "off",
+        "no-implicit-coercion": "off",
+        "no-loop-func": "error",
+        "no-useless-return": "off",
+        "no-var": "error",
+        "no-undefined": "error",
+        "no-unneeded-ternary": "error",
+        "no-param-reassign": "error",
+        "prefer-arrow-callback": "error",
+        "prefer-const": "error",
+        "require-await": "error",
+
+        "@typescript-eslint/explicit-function-return-type": "off",
+        "@typescript-eslint/no-misused-promises": [
+            "error",
+            { "checksVoidReturn": false }
+        ],
+
+        "@stylistic/arrow-parens": "error",
+        "@stylistic/brace-style": ["error", "1tbs", { "allowSingleLine": true }],
+    }
+});