streams: nil record returned by aws-sdk-go?

[mumoshu]

I occasionally see interesting errors like this:

2018-05-27T13:49:36.652Z        DEBUG   [kinesis]       streams/client.go:56    mapped to records: [{
  Data: <binary> len 1191,
  PartitionKey: "/var/lib/docker/containers/cb718fd1316624b898befeb767dd22af9dd3db4fba34c8b8f8f169cd196c5d85/cb718fd1316624b898befeb767dd22af9dd3db4fba34c8b8f8f169cd196c5d85-json.log"
} {
<中略>
} {
  Data: <binary> len 969,
  PartitionKey: "/var/lib/docker/containers/03b7c50f36b202f66f3f08fe267fc6f913f12969da348d4d4e348a9865aaf2a7/03b7c50f36b202f66f3f08fe267fc6f913f12969da348d4d4e348a9865aaf2a7-json.log"
} {
  Data: <binary> len 1131,
  PartitionKey: "/var/lib/docker/containers/6dc39940d6815b9578af296b251ab0f2a53981f318b9703155efd672214f711f/6dc39940d6815b9578af296b251ab0f2a53981f318b9703155efd672214f711f-json.log"
} {
  Data: <binary> len 3367,
  PartitionKey: "/var/lib/docker/containers/beaada804640bfdfd5c5be5cc684d60044b27891e05577b1556af65fb27c805a/beaada804640bfdfd5c5be5cc684d60044b27891e05577b1556af65fb27c805a-json.log"
}]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x7efeeda62cd6]

goroutine 76 [running]:
github.com/s12v/awsbeats/streams.processFailedDeliveries(0xc42128f980, 0x155dbe0, 0xc420554280)
        /go/src/github.com/s12v/awsbeats/streams/client.go:129 +0xe6
github.com/s12v/awsbeats/streams.(*client).Publish(0xc4202bad80, 0x155dbe0, 0xc420554280, 0xc420198e40, 0xc42023bf78)
        /go/src/github.com/s12v/awsbeats/streams/client.go:63 +0x386
github.com/elastic/beats/libbeat/outputs.(*backoffClient).Publish(0xc42011d260, 0x155dbe0, 0xc420554280, 0x0, 0x0)
        /go/src/github.com/elastic/beats/libbeat/outputs/backoff.go:43 +0x4b
github.com/elastic/beats/libbeat/publisher/pipeline.(*netClientWorker).run(0xc420082800)
        /go/src/github.com/elastic/beats/libbeat/publisher/pipeline/output.go:90 +0x1a9
created by github.com/elastic/beats/libbeat/publisher/pipeline.makeClientWorker
        /go/src/github.com/elastic/beats/libbeat/publisher/pipeline/output.go:31 +0xf0

In theory, this happens only when there is at least one nil inside records in processFailedDeliveries:

		for i, r := range records {
			if *r.ErrorCode != "" {
				failedEvents = append(failedEvents, events[i])
			}
		}

I can hardly believe it there's such a bug in aws-sdk-go, but to gather information regarding the issue, I'd like to handle nil here and emit some logs for our note.

[mumoshu]

I believe this is addressed in #31. Closing until it reproduces with actual problem(s).