Devtools hang when you try to undock them

[Nakilon]

Describe the bug
To write the cuprite/ferrum scenarios I put a ruby breakpoint, run the code, then in browser I press cmd+shift+I, then undock the devtools to move them to another display and zoom. To utilize the :save_path feature I've upgraded from 0.13 to the latest 0.14 and it seems that somewhere between ec6d9e5 and 1754c09 the devtools started hanging when you try to undock them.

To Reproduce
Also reproduced on the released gem version 0.17.1 on ruby 3.1.6 and 3.4.2

source "https://rubygems.org"
# gem "ferrum", git: "https://github.com/rubycdp/ferrum.git", ref: "ec6d9e5eee66a30b93509ef6a6bee359b84dc295" # some 0.13
# gem "ferrum", git: "https://github.com/rubycdp/ferrum.git", ref: "1754c099e9e69f0c7d1bc406ba6017fe3af70dfc" # pre 0.15
# gem "ferrum", git: "https://github.com/rubycdp/ferrum.git", ref: "e1b51b1c5c0ef7c43e0cccd334a0db72a5e6c443" # last 2.7 compatible
gem "ferrum" 

require "ferrum"
browser = Ferrum::Browser.new headless: false
browser.go_to "https://example.com"
binding.irb

Expected behavior

Screenshots

Desktop (please complete the following information):

• macOS 15.1 (24B2083)
• Google Chrome 144.0.7559.133 (официальная сборка) (arm64)

[Nakilon]

By git bisecting looks like it was broken in ec912a1
Is just passing flatten: false a proper solution? What does it do at all?