Update to message for invalid method (#5038)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/lib/server/defaultHandler.ts

@@ -4,11 +4,15 @@ type Handlers = {
   [method in "GET" | "POST" | "PATCH" | "PUT" | "DELETE"]?: Promise<{ default: NextApiHandler }>;
 };
 
-/** Allows us to split big API handlers by method and auto catch unsupported methods */
+/** Allows us to split big API handlers by method */
 const defaultHandler = (handlers: Handlers) => async (req: NextApiRequest, res: NextApiResponse) => {
   const handler = (await handlers[req.method as keyof typeof handlers])?.default;
-
-  if (!handler) return res.status(405).json({ message: "Method not allowed" });
+  // auto catch unsupported methods.
+  if (!handler) {
+    return res
+      .status(405)
+      .json({ message: `Method Not Allowed (Allow: ${Object.keys(handlers).join(",")})` });
+  }
 
   try {
     await handler(req, res);