Steps to repeat error:

• download repo to desktop
• npm install
• in one terminal: npm run start
• on another terminal npm run start:lambda

in the browser, at localhost 3000, press the buttons to call the lambda functions:

• error in console: VM271:1 Uncaught (in promise) SyntaxError: Unexpected token < in JSON at position 0

• in browser url http://localhost:9000/.netlify/functions/hello responds with hello world.

• in browser url http://localhost:9000/.netlify/functions/async-dadjoke responds with {"msg":"Request failed with status code 503"} (think that's expected).