Callback is called immediately from res.end()

[mredele]

This is not necessarily a bad thing but unlike a real express server here the instance will be suspended / terminated immediately after res.end (or res.send) and this might have some side-effects if some tear-down code was supposed to be run afterwards.

[tomas-polach]

added in branch https://github.com/archilogic-com/lambda-expressless/tree/4-callback