Jekyll does not start on Arch Linux

[link2xt]

There is no package for jekyll on Arch and jekyll is part of gemfile anyway, so "install Jekyll on your local machive" before bundle install should not be needed anyway.

After running bundle install I get this error when trying to run jekyll:

$ bundle exec jekyll
bundler: failed to load command: jekyll (/home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/bin/jekyll)
/home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/jekyll-4.3.2/lib/jekyll.rb:29:in `require': cannot load such file -- json (LoadError)
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/jekyll-4.3.2/lib/jekyll.rb:29:in `<top (required)>'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/jekyll-4.3.2/exe/jekyll:8:in `require'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/jekyll-4.3.2/exe/jekyll:8:in `<top (required)>'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/bin/jekyll:25:in `load'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/bin/jekyll:25:in `<top (required)>'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli/exec.rb:58:in `load'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli/exec.rb:58:in `kernel_load'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli/exec.rb:23:in `run'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli.rb:492:in `exec'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli.rb:34:in `dispatch'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/cli.rb:28:in `start'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/exe/bundle:45:in `block in <top (required)>'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/lib/bundler/friendly_errors.rb:117:in `with_friendly_errors'
	from /home/user/src/deltachat/deltachat-pages/vendor/bundle/ruby/3.0.0/gems/bundler-2.4.13/exe/bundle:33:in `<top (required)>'
	from /usr/bin/bundle:25:in `load'
	from /usr/bin/bundle:25:in `<main>'

It only works after running bundle add json.

[link2xt]

The question is why we even tell in the readme to install jekyll when bundle install downloads another copy of it.