In async route handlers reply.send can be used if no data is returned.
The same does not apply to the error handler function where this situation produces the log "Reply already sent".
const fastify = require('fastify')
const server = fastify({
logger: { level: "info", }
});
server.setErrorHandler(async (error, request, reply) => {
reply.code(500).send("A very bad request!");
});
server.get("/bad", {}, async (request, reply) => {
throw new Error();
});
server.get("/good", {}, async (request, reply) => {
reply.code(200).send("ok");
return;
});
server.listen(8000, '0.0.0.0')
.then()
.catch(err => {
console.log(err);
process.exit(1);
});{"level":40,"time":1535983157768,"msg":"Reply already sent","pid":60124,"hostname":"local","reqId":1,"type":"Error","stack":"Error: Reply already sent\n at _Reply.Reply.send (~/Downloads/tmp/fastify-custom-handler-issue/node_modules/fastify/lib/reply.js:44:23)\n at result.then.payload (~/Downloads/tmp/fastify-custom-handler-issue/node_modules/fastify/lib/reply.js:310:32)\n at <anonymous>\n at runMicrotasksCallback (internal/process/next_tick.js:121:5)\n at _combinedTickCallback (internal/process/next_tick.js:131:7)\n at process._tickCallback (internal/process/next_tick.js:180:9)","v":1}
In async route handlers
reply.sendcan be used if no data is returned.The same does not apply to the error handler function where this situation produces the log "Reply already sent".