sudo chef-server-ctl reconfigure on Ubuntu 18.04 failed

I'm trying to install chef-server on a Ubuntu 18.04 instance, but it failes:

wget https://packages.chef.io/files/stable/chef-server/12.19.31/ubuntu/18.04/chef-server-core_12.19.31-1_amd64.deb

sudo dpkg -i chef-server-core_12.19.31-1_amd64.deb
sudo chef-server-ctl reconfigure

Full output: https://gist.github.com/stephanvierkant/04791b5d28185ebd603920f131723556

Chef Client failed. 341 resources updated in 02 minutes 05 seconds
[2019-03-13T10:07:27+00:00] FATAL: Stacktrace dumped to /var/opt/opscode/local-mode-cache/chef-stacktrace.out
[2019-03-13T10:07:27+00:00] FATAL: Please provide the contents of the stacktrace.out file if you file a bug report
[2019-03-13T10:07:27+00:00] FATAL: Chef::Exceptions::MultipleFailures: Multiple failures occurred:
* TypeError occurred in chef run: openssl_x509_certificate[/var/opt/opscode/nginx/ca/.crt] (private-chef::nginx line 77) had an error: TypeError: no implicit conversion of nil into String
* Mixlib::ShellOut::ShellCommandFailed occurred in delayed notification: runit_service[nginx] (private-chef::nginx line 37) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
---- Begin output of /opt/opscode/embedded/bin/sv restart /opt/opscode/service/nginx ----
STDOUT: fail: /opt/opscode/service/nginx: unable to change to service directory: file does not exist
STDERR: 
---- End output of /opt/opscode/embedded/bin/sv restart /opt/opscode/service/nginx ----
Ran /opt/opscode/embedded/bin/sv restart /opt/opscode/service/nginx returned 1
* Mixlib::ShellOut::ShellCommandFailed occurred in delayed notification: execute[set initial migration level] (private-chef::partybus line 59) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
---- Begin output of cd /opt/opscode/embedded/service/partybus && ./bin/partybus init ----
STDOUT: 
STDERR: /opt/opscode/embedded/service/gem/ruby/2.5.0/gems/sequel-3.34.1/lib/sequel/database/schema_generator.rb:19: warning: constant ::Fixnum is deprecated
/opt/opscode/embedded/service/gem/ruby/2.5.0/gems/sequel-3.34.1/lib/sequel/database/schema_generator.rb:19: warning: constant ::Bignum is deprecated
./bin/partybus:11:in `require': cannot load such file -- /opt/opscode/embedded/service/partybus/config.rb (LoadError)
        from ./bin/partybus:11:in `<main>'
---- End output of cd /opt/opscode/embedded/service/partybus && ./bin/partybus init ----
Ran cd /opt/opscode/embedded/service/partybus && ./bin/partybus init returned 1

================================================================================
   Error executing action `create` on resource 'openssl_x509_certificate[/var/opt/opscode/nginx/ca/.crt]'
   ================================================================================
   
   TypeError
   ---------
   no implicit conversion of nil into String
   
   Resource Declaration:
   ---------------------
   # In /var/opt/opscode/local-mode-cache/cookbooks/private-chef/recipes/nginx.rb
   
    77:    openssl_x509_certificate ssl_crtfile do
    78:      common_name server_name
    79:      org node['private_chef']['nginx']['ssl_company_name']
    80:      org_unit node['private_chef']['nginx']['ssl_organizational_unit_name']
    81:      country node['private_chef']['nginx']['ssl_country_name']
    82:      key_length node['private_chef']['nginx']['ssl_key_length']
    83:      expire node['private_chef']['nginx']['ssl_duration']
    84:      subject_alt_name [ "#{server_name_type}:#{server_name}" ]
    85:      owner OmnibusHelper.new(node).ownership['owner']
    86:      group OmnibusHelper.new(node).ownership['group']
    87:      mode '0600'
    88:    end
    89: 

This is caused by not having a hostname set. I think a better error message should be given here.

Start with /var/opt/opscode/local-mode-cache/cookbooks/private-chef/recipes/nginx.rb at line 77 and reproduce the failure with chef-server-ctl reconfigure on Ubuntu 18.04 without a hostname. Trace the hostname-related failure and verify that reconfigure reports a clearer error explaining the missing hostname.