error: Cannot read properties of undefined (reading 'resurrectTimeout')

[pmuellr]

On Kibana main, using @elastic/transport 8.7.0

We've started to see some errors with resurrectTimeout like the following: Cannot read properties of undefined (reading 'resurrectTimeout'). These seem to have started when we changed our access patterns against an index - different operations and different frequency. Haven't yet looked into any other context on them, but figured I'd go ahead and at least post here that we are seeing them.

[pmuellr]

Issue we are tracking within Kibana: elastic/kibana#196379

[pmuellr]

Took a quick peek at the code, seems like it's going to be one of the references after this.connections.find(), which can return undefined. Presumably there's a race condition somewhere removing the connection? I saw two references like this, in that module.
This would align with the changes we made, where we are making ES calls at a faster rate than before (when we didn't see this often). More chances for a race.

elastic-transport-js/src/pool/ClusterConnectionPool.ts

Lines 151 to 156 in 3374510

	const connection = this.connections.find(c => c.id === this.dead[0]) as Connection
	if (opts.now < connection.resurrectTimeout) {
	debug('Nothing to resurrect')
	return
	}