UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce the problem:
1. Attempt to load a page and it fail to load (Main frame request failed to load)

OR

1a. Load a page which contains an iFrame which fails to load (The subframe request failed to load).

What is the expected behavior?
Be able to easily distinguish whether it was the main frame or the subframe that failed to load. 

What went wrong?
The current recommended process involves: 

"Network.loadingFailed has a requestId, for which Network.requestWillBeSent reports frameId. You can use Page.getFrameTree to get all the frames with their ids, and also follow Page.frameXXX events if frames can change over time."

This seems fairly involved for information that is fairly easy to expose. 

Did this work before? N/A 

Chrome version: 73.0.3642.0  Channel: dev
OS Version: 
Flash Version: 

https://groups.google.com/a/chromium.org/forum/#!topic/headless-dev/5WK4UffcEW0