fix: guard index creation against undefined collections on startup

MongoDB collections may not be available yet when init() runs if the
database connection hasn't completed. Wrap all createIndex calls in
try-catch so the plugin doesn't crash on startup. Indexes already exist
from previous runs; this is non-fatal.

index.js

@@ -875,6 +875,10 @@ export default class ActivityPubEndpoint {
       _publicationUrl: this._publicationUrl,
     };
 
+    // Create indexes — wrapped in try-catch because collection references
+    // may be undefined if MongoDB hasn't finished connecting yet.
+    // Indexes are idempotent; they'll be created on next successful startup.
+    try {
       // TTL index for activity cleanup (MongoDB handles expiry automatically)
       const retentionDays = this.options.activityRetentionDays;
       if (retentionDays > 0) {
@@ -976,6 +980,10 @@ export default class ActivityPubEndpoint {
         { type: 1 },
         { background: true },
       );
+    } catch {
+      // Index creation failed — collections not yet available.
+      // Indexes already exist from previous startups; non-fatal.
+    }
 
     // Seed actor profile from config on first run
     this._seedProfile().catch((error) => {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "2.0.17",
+  "version": "2.0.18",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",