fix: WebFinger returns 500 (#9390)

packages/backend/src/server/WellKnownServerService.ts

@@ -11,6 +11,7 @@ import { NodeinfoServerService } from './NodeinfoServerService.js';
 import type { FindOptionsWhere } from 'typeorm';
 import { bindThis } from '@/decorators.js';
 import type { FastifyInstance, FastifyPluginOptions } from 'fastify';
+import fastifyAccepts from '@fastify/accepts';
 
 @Injectable()
 export class WellKnownServerService {
@@ -41,6 +42,8 @@ export class WellKnownServerService {
 		const jrd = 'application/jrd+json';
 		const xrd = 'application/xrd+xml';
 
+		fastify.register(fastifyAccepts);
+
 		fastify.addHook('onRequest', (request, reply, done) => {
 			reply.header('Access-Control-Allow-Headers', 'Accept');
 			reply.header('Access-Control-Allow-Methods', 'GET, OPTIONS');