enhance: fallback option for media proxy

packages/backend/src/server/MediaProxyServerService.ts

@@ -1,7 +1,10 @@
 import * as fs from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname } from 'node:path';
 import { Inject, Injectable } from '@nestjs/common';
 import { FastifyInstance, FastifyPluginOptions, FastifyReply, FastifyRequest } from 'fastify';
 import sharp from 'sharp';
+import fastifyStatic from '@fastify/static';
 import { DI } from '@/di-symbols.js';
 import type { Config } from '@/config.js';
 import { isMimeImage } from '@/misc/is-mime-image.js';
@@ -16,6 +19,11 @@ import { FileInfoService } from '@/core/FileInfoService.js';
 import { LoggerService } from '@/core/LoggerService.js';
 import { bindThis } from '@/decorators.js';
 
+const _filename = fileURLToPath(import.meta.url);
+const _dirname = dirname(_filename);
+
+const assets = `${_dirname}/../../server/file/assets/`;
+
 @Injectable()
 export class MediaProxyServerService {
 	private logger: Logger;
@@ -41,6 +49,11 @@ export class MediaProxyServerService {
 			done();
 		});
 
+		fastify.register(fastifyStatic, {
+			root: _dirname,
+			serve: false,
+		});
+
 		fastify.get<{
 			Params: { url: string; };
 			Querystring: { url?: string; };
@@ -125,6 +138,10 @@ export class MediaProxyServerService {
 			return image.data;
 		} catch (err) {
 			this.logger.error(`${err}`);
+
+			if ('fallback' in request.query) {
+				return reply.sendFile('/dummy.png', assets);
+			}
 	
 			if (err instanceof StatusError && (err.statusCode === 302 || err.isClientError)) {
 				reply.code(err.statusCode);