Silent failures

[rclark]

Very rarely, streambot-wrapped functions appear to fail silently, before the service function even gets called. This manifests as logs that look like:

2016-01-12T22:19:44.046Z    257dba2f-de7b-464c-acd1-6e906c32ea4b    Start time: 2016-01-12T22:19:44.046Z
2016-01-12T22:19:44.046Z    257dba2f-de7b-464c-acd1-6e906c32ea4b    Load Environment: {"TableName":"streambot-env","Key":{"name":{"S":"my-function-name"}}}
END RequestId: 257dba2f-de7b-464c-acd1-6e906c32ea4b
REPORT RequestId: 257dba2f-de7b-464c-acd1-6e906c32ea4b  Duration: 70.84 ms  Billed Duration: 100 ms     Memory Size: 750 MB Max Memory Used: 41 MB
Process exited before completing request

• very short invocation
• logs that is is going to make a dynamodb.getItem request
• does not encounter / log an error with the getItem request
• does not log that there was nothing read from dynamodb
• does not log that any requests failed and were retried by the aws-sdk

I really can't see any way for the function to fail here --- and there's not a lot of code. Plus, syntax errors or other failures ought to result in something getting logged. These functions seem to just... vanish.