feat: add respondWithError() function

Author: boywithkeyboard

respondWithError.ts

@@ -0,0 +1,15 @@
+const ERRORS = {
+  BAD_MODULE: 400,
+  BAD_VERSION: 400,
+  UNINDEXED_MODULE: 404,
+  NOT_FOUND: 404,
+}
+
+export function respondWithError(message: keyof typeof ERRORS) {
+  return new Response(message, {
+    status: ERRORS[message],
+    headers: {
+      'content-type': 'text/plain; charset=utf-8',
+    },
+  })
+}