Fix throwing non-new Errors and literals (#1338)

* Add linting to enforce `new Error()`
* Fix throwing non-new Errors and literals

.prettierignore

@@ -3,6 +3,7 @@
 
 # Opt-ins
 !GOVERNANCE.md
+!eslint.config.js
 
 !/features/*.yml
 /features/*.yml.dist

eslint.config.js

@@ -0,0 +1,24 @@
+import newWithError from "eslint-plugin-new-with-error";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(tseslint.configs.base, {
+  plugins: { newWithError },
+  rules: {
+    "no-throw-literal": "error",
+    "newWithError/new-with-error": "error",
+  },
+  files: ["**/*.ts"],
+});
+
+// TODO: do linting more comprehensively, something like:
+// import eslint from "@eslint/js";
+// export default tseslint.config(
+//   eslint.configs.recommendedTypeChecked,
+//   ...tseslint.configs.recommended,
+//   {
+//     plugins: { newWithError },
+//     rules: {
+//       "no-throw-literal": "error",
+//       "newWithError/new-with-error": "error",
+//   },
+// );