fix lint errors

packages/slackbot-proxy/src/filters/ResourceNotFoundFilter.ts

@@ -1,18 +1,22 @@
-import {Catch, ExceptionFilterMethods, PlatformContext, ResourceNotFound} from "@tsed/common";
+import {
+  Catch, ExceptionFilterMethods, PlatformContext, PlatformResponse, ResourceNotFound,
+} from '@tsed/common';
 
 @Catch(ResourceNotFound)
 export class ResourceNotFoundFilter implements ExceptionFilterMethods {
-  async catch(exception: ResourceNotFound, ctx: PlatformContext) {
-    const {response} = ctx;
+
+  async catch(exception: ResourceNotFound, ctx: PlatformContext): Promise<PlatformResponse<any>> {
+    const { response } = ctx;
 
     const obj = {
       status: exception.status,
       message: exception.message,
-      url: exception.url
+      url: exception.url,
     };
 
     return response
       .status(exception.status)
       .body(obj);
   }
+
 }