`lambda is not a function` error thrown when handler is misspelled

This is a (Bug Report)

Description

A Type Error is thrown (lambda is not a function) when the handler within serverless.yml is misspelled and the function is invoked locally. I feel like there could be a better check / error to report such an error.

For bug reports:

• What went wrong?

• What did you expect should have happened? A more useful error message

• What was the config you used? Any basic helloworld serverless.yml will do the trick.

• What stacktrace or error message from your provider did you see? nil

Additional Data

To fix this bug, within the serverless.yml I went from:

createThingType:
    handler: handler.createThing

to:

createThingType:
    handler: handler.createThingType

There was no function in the handler file called createThing but there was a method called createThingType. Function was invoked using the following: $ DEBUG=* sls invoke local -f createThingType.

• Provider Error messages: Type Error: lambda is not a function

[HoraceShmorace]

What is your proposal for a better error message? Imo, the error message that it is not a function is quite right here. Maybe telling, that the handler export does not exist would be a slight improvement though.

lambda is not a function is a terrible error message. I had no idea it meant that it couldn’t find the handler I specified. Couldn't find the specified handler function would be better.

[kbariotis]

@shahzeb1 I am suspecting that AWS doesn’t allows a handler file to export anything than a handler function. Correct me if I am wrong.

@HyperBrain +1 to add a check on whether the defined exported name is has actually been exported. We could also list all the exported functions of the file as a suggestion, like:

The handler doesn't export a function called "createThing". Did you mean "createThingType", "createAnotherThingType"?