V3: serverless offline does not work with the elm and shebang loader

[HyperBrain]

This is a Bug Report

Description

If you try to run the serverless-elm-demo with serverless-offline and do not specify the offline location as .webpack/service the server will crash when you access one of the sample endpoints.

However the elm files are compiled correctly and also the service packages are created correctly.

For more details see here: ktonon/elm-serverless-demo#3

Solution

serverless-webpack should set the location option of serverless-offline automatically to the base path of the compiled outputs (i.e. .webpack/service or any user specified webpack base path).

Additional Data

• Serverless-Webpack Version you're using: 3.0.0-rc.1
• Webpack version you're using: ^3.3.0 -> 3.5.4
• Serverless Framework Version you're using: 1.19.0
• Operating System: ALL

[HyperBrain]

/cc @ktonon @ringods