[@types/pg] err param in "release" | "error" event handler callback should have type Error | null | undefined

[RalphORama]

Using:

• "pg": "^8.11.3",
• "@types/pg": "^8.10.9",

Specifically on this line: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/pg/index.d.ts#L206

on(event: "release" | "error", listener: (err: Error, client: PoolClient) => void): this;

It often occurs that the err parameter is of type null or undefined. I encountered an issue because checking err.message in a custom event listener for the release event can result in:

[pgPool]	query dispatched
/app/node_modules/pg/lib/query.js:143
          throw err
          ^
|
TypeError: Cannot read properties of null (reading 'message')
    at BoundPool.<anonymous> (/app/dist/bot/database/CustomPool.js:81:75)
    at BoundPool.emit (node:events:514:28)
    at BoundPool._release (/app/node_modules/pg-pool/index.js:338:10)
    at Client.release (/app/node_modules/pg-pool/index.js:327:12)
    at /app/node_modules/pg-pool/index.js:424:18
    at query.callback (/app/node_modules/pg/lib/client.js:559:9)
    at Query.handleReadyForQuery (/app/node_modules/pg/lib/query.js:139:14)
    at Client._handleReadyForQuery (/app/node_modules/pg/lib/client.js:312:19)
    at Connection.emit (node:events:514:28)
    at /app/node_modules/pg/lib/connection.js:117:12
|
Node.js v20.10.0
exited with code 1

A temporary workaround I'm using is:

pool.on("release", (err) => {
  console.error(`[CustomPool]\tClient released back to pool:\t${String(err)}`);
});

which will often log messages like:

[CustomPool]	Client released back to pool:	null
[CustomPool]	Client released back to pool:	undefined

[typescript-bot]

Thanks for the discussion about "pg", some useful links for everyone:

• npm
• DT
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Pinging the DT module owners: @pspeter3, @HoldYourWaffle.