Hello!

After update to ~> 4.4.0 (couldn't set the affect version unfortunately), using fetch on BSON::Document objects might fail - new fetch definition which overshadows Hash one has different set of arguments:

bson-ruby

https://github.com/mongodb/bson-ruby/blob/v4.4.1/lib/bson/document.rb#L50-L53

fetch(key)

ruby core

https://ruby-doc.org/core-2.5.1/Hash.html#method-i-fetch
 
fetch(key [, default] ) → obj
fetch(key) {| key | block } → obj
 
Best,
Michał