Heroku R13 Error - Type Error, can't convert nil into string about janky HOT 3 CLOSED

Can you paste the full backtrace? (there should be a bunch of text after TypeError - can't convert nil into String:)

from janky.

/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/cookie.rb:152:in 'hexdigest'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/cookie.rb:152:in 'generate_hmac'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/cookie.rb:109:in 'unpacked_cookie_data'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/cookie.rb:99:in 'extract_session_id'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:43:in 'load_session_id!'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:32:in '[]'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:262:in 'current_session_id'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:268:in 'session_exists?'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:107:in 'exists?'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:64:in 'has_key?'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:122:in 'load_for_read!'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:43:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/path_traversal.rb:16:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/json_csrf.rb:17:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/session_hijacking.rb:22:in 'accepts?'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:200:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/head.rb:9:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1334:in 'block in call'

`````` /app/ven```

/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/session/abstract/id.rb:205:in 'context'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/nulllogger.rb:9:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1416:in 'synchronize'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:835:in 'route_missing'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:796:in 'route!'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:886:in 'dispatch!'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:719:in 'block in call!'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1334:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:871:in 'block in invoke'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:871:in 'catch'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:871:in 'invoke'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:719:in 'call!'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:792:in 'route!'
/app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:705:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/path_traversal.rb:16:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/json_csrf.rb:17:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/nulllogger.rb:9:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/head.rb:9:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/urlmap.r

/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/urlmap.rb:49:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/builder.rb:134:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/janky-0.9.0/lib/janky/exception.rb:44:in 'call'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/connection.rb:80:in 'block in pre_process'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/connection.rb:78:in 'pre_process'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/connection.rb:53:in 'process'
/app/vendor/bundle/ruby/1.9.1/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in 'run'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/connection.rb:38:in 'receive_data'
/app/vendor/bundle/ruby/1.9.1/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in 'run_machine'
/app/vendor/bundle/ruby/1.9.1/gems/rack-1.4.0/lib/rack/urlmap.rb:64:in 'block in call'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/controllers/controller.rb:86:in 'start'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/connection.rb:78:in 'catch'
/app/vendor/bundle/ruby/1.9.1/bin/thin:19:in 'load'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/backends/base.rb:61:in 'start'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/server.rb:159:in 'start'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/bin/thin:6:in '<top (required)>'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/runner.rb:151:in 'run!'
/app/vendor/bundle/ruby/1.9.1/bin/thin:19:in '<main>'
/app/vendor/bundle/ruby/1.9.1/gems/thin-1.3.1/lib/thin/runner.rb:185:in 'run_command'

from janky.

Make sure that the JANKY_SESSION_SECRET config variable is set with heroku config:add JANKY_SESSION_SECRET=something-random-and-secret

from janky.