Lambda is returning headers in body of request - express

Question

I am using serverless to deploy my express js application in lambda. The weird thing is that some apis are returning headers in the body of the response I am not sure why this is happening. Here is my serverless YAML file:
org: test
app: test-api
# serverless.yml
service: test-api
package:
exclude:
#- node_modules/**
- __tests__/**
provider:
name: aws
runtime: nodejs10.x
region: us-east-1
environment:
SERVICE_NAME: ${self:service}
plugins:
- serverless-domain-manager
custom:
stage: ${opt:stage, dev}
domains:
prod: api.test.com
dev: dev-api.test.com
customDomain:
basePath: "${self:provider.environment.SERVICE_NAME}"
domainName: ${self:custom.domains.${self:custom.stage}}
stage: "${self:custom.stage}"
createRoute53Record: true
functions:
test-api:
handler: build/app.handler
environment:
stage: ${self:custom.stage}
events:
- http:
path: v1/s
method: GET
cors: true
- http:
path: v1/sc
method: GET
cors: true
- http:
path: v1/s/{s}
method: GET
cors: true
- http:
path: v1/cs
method: POST
cors: true
- http:
path: v1/s
method: POST
cors: true
- http:
path: v1/s/{s}
method: DELETE
cors: true
- http:
path: v1/s/{s}
method: PUT
cors: true
Here is what the response looks like:
curl -d '{"c":"test"}' -H "Content-Type: application/json" -X POST https://dev-api.test.com/test-api/v1/cs
HTTP/1.1 200 Not Modified
X-Powered-By: Express
Access-Control-Allow-Origin: *
Access-Control-Expose-Headers: sessionId
Vary: Origin
Content-Type: application/json; charset=utf-8
Content-Length: 55
ETag: W/"37-vmzwGqI9Wb8ACGS7qhhE3/JBqt4"
Date: Fri, 24 Apr 2020 12:30:41 GMT
Connection: keep-alive
{"rsp":{"msg":{"s":[],"c":{}},"err":null}
Any idea if its the serverless yaml or some other configuration?

Answer 1

I was able to fix this, contacted serverless support and they said there was a bug and now it has been fixed. Just need to update serverless and it was resolved!

Answer 2

Looks like you enabled the -i option of curl? Has curl an alias?