I get the following error

"error_message":"Display socket is taken but lock file is missing - check the Headless troubleshooting guide","error_class":"Headless::Exception","failed_at":1564710065.787636,"retry_count":0,"error_backtrace":["/Users/buzz/.gem/ruby/2.6.3/gems/headless-2.3.1/lib/headless.rb:207:in `ensure_xvfb_launched'","/Users/buzz/.gem/ruby/2.6.3/gems/headless-2.3.1/lib/headless.rb:195:in `launch_xvfb'","/Users/buzz/.gem/ruby/2.6.3/gems/headless-2.3.1/lib/headless.rb:182:in `block in pick_available_display'"