Internal Server Error will occur if I add type annotation to the route functions

[studio3104]

When I deployed after giving type annotation to my existing implementation as below, Internal Server Error occurred at all endpoints.

@app.route('/')
def index() -> Dict[str, str]:
    return {'hello': 'world'}

My deployment is done via a pipeline based on the definition generated by chalice generate-pipeline command.

Though I created a new environment to try to reproduce my issue, I could not make it reproduced. (I mean I could access to my API normally even if the method has type annotation.)

If I re-deploy the code that was deleted the type annotation via the existing pipeline, I can access normally without facing an Internal Server Error.

Submitting a reproduction code is difficult for me, but is there anything I can confirm else?

[studio3104]

My local environment

$ chalice --version
chalice 1.6.2, python 3.7.1, darwin 17.7.0

[studio3104]

I'm really sorry for making organizers bothering, but I got succeeded with 3.6.
Originally, 3.7 shouldn't have been supported for now, I tried with my custom code at the time...

[studio3104]

Custom code is this #1045
Probably I need to close this PR as well...?