Filtering breadcrumbs in a `beforeNotify`

[rabidpraxis]

We had a customer reach out about filtering breadcrumbs, so I looked into recommending a beforeNotify snippet to remove unwanted breadcrumbs.

I could not get it to work, as the filtered breadcrumbs would not persist in the final payload. Now, I understand that accessing a field with double underscores (__breadcrumbs) is generally a no-no. Is there a way to do this that I am unaware of?

I pushed up a test in a branch with how I thought it would work:

https://github.com/honeybadger-io/honeybadger-js/compare/master...filter-breadcrumbs