AWS Lambda Function (Node) - Custom timeout logging - node.js

Question

I'm wondering if there is any way of hijacking the standard "Task timed out after 1.00 seconds" log.
Bit of context : I'm streaming lambda function logs into AWS Elasticsearch / Kibana, and one of the things I'm logging is whether or not the function successfully executed (good to know). I've set up a test stream to ES, and I've been able to define a pattern to map what I'm logging to fields in ES.
From the function, I console log something like:
"\"FAIL\"\"Something messed up\"\"0.100 seconds\""
and with the mapping, I get a log structure like:
Status - Message -------------------- Execution Time
FAIL ---- Something messed up --- 0.100 seconds
... Which is lovely. However if a log comes in like:
"Task timed out after 1.00 seconds"
then the mapping will obviously not apply. If it's picked up by ES it will likely dump the whole string into "Status", which is not ideal.
I thought perhaps I could query context.getRemainingMillis() and if it goes maybe within 10 ms of the max execution time (which you can't get from the context object??) then fire the custom log and ignore the default output. This however feels like a hack.
Does anyone have much experience with logging from AWS Lambda into ES? The key to creating these custom logs with status etc is so that we can monitor the activity of the lambda functions (many), and the default log formats don't allow us to classify the result of the function.
**** EDIT ****
The solution I went with was to modify the lambda function generated by AWS for sending log lines to Elasticsearch. It would be nice if I could interface with AWS's lambda logger to set the log format, however for now this will do!
I'll share a couple key points about this:
The work done for parsing the line and setting the custom fields is done in transform() before the call to buildSource().
The message itself (full log line) is found in logEvent.message.
You don't just reassign the message in the desired format (in fact leaving it be is probably best since the raw line is sent to ES). The key here is to set the custom fields in logEvent.extractedFields. So once I've ripped apart the log line, I set logEvent.extractedFields.status = "FAIL", logEvent.extractedFields.message = "Whoops.", etc etc.