Bad data causes confusing error message on registerFunction

[rupakg]

Here is the API call:

curl -X POST http://localhost:8056/v1/functions \
  -d '{
	"functionId": "some-unique-function", 
	"provider": {
		"type": "awslambda",
		"arn": "arn:aws:lambda:us-east-1:063733696545:function:user-service-prod-some-unique-function", 
		"region": "us-east-1",
	}
}'

and the response:

{
    "error": "Function \"\" already registered."
}

The issue with this call is the extra trailing , after the region in the data. Most JS devs, love to leave that trailing , everywhere :) This error message can cause confusion.