Getting ERR_EMPTY_RESPONSE with sls run, working fine with invoke (local or not)


I have a lambda that returns a JSON based on an API response, which may contain an array with over than 2000 items.

Basically, if you sls run --watch then open http://localhost:400/hello, it works fine. But if you change this for(let i = 0; i < 2000; i++) { to loop anything over 2200 it fails, the browser gets ERR_EMPTY_RESPONSE. The interesting part is that, it only fails on sls run it works fine with sls invoke (local or not)

Any ideas on what it could be?

service: hello

  name: aws
  runtime: nodejs6.10

    handler: hello.handler
      - http:
          path: hello
          method: get
          cors: true

export const handler = async (event, context, callback) => {
  let items = []
  // 2000 works
  // 2200 fails ERR_EMPTY_RESPONSE

  for(let i = 0; i < 2000; i++) {
    items.push({ "id": i })

  const data = { "items_size": items.length, "items": items }

  callback(null, { statusCode: '200',
                   body: JSON.stringify(data),
                   headers: {
                     'Content-Type': 'application/json',
                     'Access-Control-Allow-Origin': '*',
                     'Access-Control-Allow-Credentials': true