aws-xray-sdk-go: "segment cannot be found" in lambda function

I’m new to X-Ray and am trying to integrate it into a Lambda function called from API Gateway as a Lambda proxy integration request. My code follows this example:

xray.Configure(xray.Config{LogLevel: "trace"})
sess := session.Must(session.NewSession())
dynamo := dynamodb.New(sess)
xray.AWS(dynamo.Client)

This results in the following error being logged Error Suppressing AWS X-Ray context missing panic: failed to begin subsegment named 'dynamodb': segment cannot be found., which is followed by a panic runtime error: invalid memory address or nil pointer dereference in the xray SDK when the first DynamoDB operation executes.

I can “fix” this by creating a new segment with xray.BeginSegment, which puts a new service node in the graph.

I have tried this both with “active tracing” enabled and disabled in the Lambda config. When enabled, I get 2 more nodes for the Lambda service and function in the graph, but they’re not connected to the new segment I create in the function as described above.

I am not sure if I’m doing something wrong (in which case the example would seem wrong too) or if this is a bug.

It also worries me that this results in a panic that propagates to my Lambda, because even if I fix this particular problem, I don’t like the idea of a library that just instruments my code potentially causing a fatal error of the lambda.