fix: validate DIDs before generating keys.

main.ts

···
 import { IdResolver } from "npm:@atproto/identity@0.4.3";
 import * as earthstar from "jsr:@earthstar/earthstar@11.0.0-beta.7";
 import { encodeBase32 } from "jsr:@std/encoding@1.0.6/base32";
+import { assertDid } from "npm:@atproto/did@0.1.3";
 
 type Keypair = { publicKey: Uint8Array; secretKey: Uint8Array };
 
···
 // Get a user's public key
 router.get("/xrpc/public.key.pigeon.muni.town", async ({ query }) => {
   const { did } = query;
+  try {
+    assertDid(did);
+  } catch (e) {
+    return error(400, `Invalid DID: ${e}`);
+  }
   if (typeof did !== "string" || !did)
     return error(400, "DID query parameter required");
   return {