{"action":"closed","issue":{"url":"https://api.github.com/repos/koajs/koa/issues/600","labels_url":"https://api.github.com/repos/koajs/koa/issues/600/labels{/name}","comments_url":"https://api.github.com/repos/koajs/koa/issues/600/comments","events_url":"https://api.github.com/repos/koajs/koa/issues/600/events","html_url":"https://github.com/koajs/koa/issues/600","id":118124125,"number":600,"title":"Error thrown twice","user":{"login":"dacodekid","id":10047844,"avatar_url":"https://avatars.githubusercontent.com/u/10047844?v=3","gravatar_id":"","url":"https://api.github.com/users/dacodekid","html_url":"https://github.com/dacodekid","followers_url":"https://api.github.com/users/dacodekid/followers","following_url":"https://api.github.com/users/dacodekid/following{/other_user}","gists_url":"https://api.github.com/users/dacodekid/gists{/gist_id}","starred_url":"https://api.github.com/users/dacodekid/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/dacodekid/subscriptions","organizations_url":"https://api.github.com/users/dacodekid/orgs","repos_url":"https://api.github.com/users/dacodekid/repos","events_url":"https://api.github.com/users/dacodekid/events{/privacy}","received_events_url":"https://api.github.com/users/dacodekid/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-11-20T20:55:21Z","updated_at":"2015-11-20T21:41:43Z","closed_at":"2015-11-20T21:41:43Z","body":"Is this expected behavior?\r\n\r\n```javascript\r\nconst Koa = require('koa');\r\nconst app = new Koa();\r\n\r\napp.use((ctx, next) => {\r\n  throw new Error();\r\n});\r\n\r\napp.listen(3000);\r\n```\r\n\r\n```sh\r\n  Error\r\n      at one.js:6:9\r\n      at dispatch (/Users/dacodekid/dev/koa-hpa/node_modules/koa-compose/index.js:41:32)\r\n      at /Users/dacodekid/dev/koa-hpa/node_modules/koa-compose/index.js:34:12\r\n      at Server.<anonymous> (/Users/dacodekid/dev/koa-hpa/node_modules/koa/lib/application.js:126:7)\r\n      at emitTwo (events.js:87:13)\r\n      at Server.emit (events.js:172:7)\r\n      at HTTPParser.parserOnIncoming [as onIncoming] (_http_server.js:527:12)\r\n      at HTTPParser.parserOnHeadersComplete (_http_common.js:88:23)\r\n\r\n\r\n  Error\r\n      at one.js:6:9\r\n      at dispatch (/Users/dacodekid/dev/koa-hpa/node_modules/koa-compose/index.js:41:32)\r\n      at /Users/dacodekid/dev/koa-hpa/node_modules/koa-compose/index.js:34:12\r\n      at Server.<anonymous> (/Users/dacodekid/dev/koa-hpa/node_modules/koa/lib/application.js:126:7)\r\n      at emitTwo (events.js:87:13)\r\n      at Server.emit (events.js:172:7)\r\n      at HTTPParser.parserOnIncoming [as onIncoming] (_http_server.js:527:12)\r\n      at HTTPParser.parserOnHeadersComplete (_http_common.js:88:23)\r\n```"}}