Appsync subscriptions error handler is not called consistently

[ghost]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
When appsync-sdk loses internet with an active subscription, the error handler is not called immediately. After a timeout of about 5 minutes, appsync-sdk will begin retries. After some amount of retries, the error handler is sometimes called, but this is not consistent.

To see when appsync-sdk begins retries, set DEBUG=aws-appsync:* in environment variables.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.
Create a successful appsync subscription and remove internet. Wait for up to 15 minutes, and repeat to see if the error handler is called.

What is the expected behavior?
When appsync-sdk loses internet with an active subscription, there should be a timeout, but after some time, the error handler should be called.

Which versions and which environment (browser, react-native, nodejs) / OS are affected by this issue? Did this work in previous versions?
Nodejs 12.14.0, windows 10 pro 1909, appsync-sdk 3.0.2.
Previous versions have not been tried.

This is mostly an issue for logging reasons. We currently have no idea when appsync-sdk has lost it's internet connection, or if a subscription has failed for a certain amount of time.