How to prevent Kysely from crashing node app if database goes down about kysely HOT 6 OPEN

I'm not seeing any uncaught exception errors in the log, so it's unclear what's actually crashing the server.

@igalklebanov Any ideas? Could it be we're not listening to the error event and it "leaks out"?

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I think this is something Kysely should do automatically

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@koskimas @AnthonyPhan Yeah, haven't handled this one by mistake. Let's do it.

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Are you absolutely sure you don't have some call somewhere without an exception handler? The stack trace shows the error comes all the way up to the execute method. After that it's just a standard Promise. We don't do anything special there. I don't see how this could be caused by Kysely.

Try converting all kysely calls to await syntax. That way you get the stack trace all the way up to your own code.

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Hi @koskimas

Thanks for pointer. I went back over the code base to check for instances of execute() without a catch and did find a few, this was the cause of the error above.

However after I ensure a .catch on all instance of execute() i'm still able to crash the node serve by toggling the SQL db off and on. Im not sure if this is actually due to Kysely however i've attached an error log below incase you can spot the issue.

/Users/anthonyphan/repos/nex-gps/node_modules/tedious/src/connection.ts:2313
      this.emit('error', new ConnectionError(message, 'ESOCKET'));
                         ^
ConnectionError: Connection lost - socket hang up
    at Connection.socketError (/Users/anthonyphan/repos/nex-gps/node_modules/tedious/src/connection.ts:2313:26)
    at Connection.socketEnd (/Users/anthonyphan/repos/nex-gps/node_modules/tedious/src/connection.ts:2326:12)
    at Socket.<anonymous> (/Users/anthonyphan/repos/nex-gps/node_modules/tedious/src/connection.ts:1997:35)
    at Socket.emit (node:events:525:35)
    at Socket.emit (node:domain:489:12)
    at endReadableNT (node:internal/streams/readable:1359:12)
    at processTicksAndRejections (node:internal/process/task_queues:82:21) {
  code: 'ESOCKET'
}
[nodemon] app crashed - waiting for file changes before starting...

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I think i might have resolved the issue by creating the the dialect as show below with the error handler. Unsure if this is classed as user error or if the Kysely library should of caught that error. Either way i'm happy that we got to the bottom of it :) Appreciate the help!

import { Database } from './types.ts' // this is the Database interface we defined earlier
import * as tedious from 'tedious'
import * as tarn from 'tarn'
import { Kysely, MssqlDialect } from 'kysely'

const dialect = new MssqlDialect({
  tarn: {
    ...tarn,
    options: {
      min: 0,
      max: 10,
    },
  },
  tedious: {
    ...tedious,
    connectionFactory: () => new tedious.Connection({
      authentication: {
        options: {
          password: 'password',
          userName: 'username',
        },
        type: 'default',
      },
      options: {
        database: 'some_db',
        port: 1433,
        trustServerCertificate: true,
      },
      server: 'localhost',
    }).on('error', console.log),    //THIS LINE RESOLVES THE ISSUE
  },
})

// Database interface is passed to Kysely's constructor, and from now on, Kysely 
// knows your database structure.
// Dialect is passed to Kysely's constructor, and from now on, Kysely knows how 
// to communicate with your database.
export const db = new Kysely<Database>({
  dialect,
})

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