error when running ruby server on replit

[gulkily]

~/LessonAug21/thimble$ ruby start_server.rb
internal:/nix/store/yfbi30xd53mnsh4ax1zppmr5bsr2r669-ruby-3.0.4/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb:85:in require': cannot load such file -- webrick (LoadError) from <internal:/nix/store/yfbi30xd53mnsh4ax1zppmr5bsr2r669-ruby-3.0.4/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in require'
from start_server.rb:32:in `

'

[gulkily]

workaround: gem install webrick