Getting a rack exception with rack-mini-profiler

[ali-bugdayci]

Hi,

Mini profiler is quite popular these days. I am getting the following exception both in rails 3.2 and 4.

Its working fine with rails server command. Since rails is using a rack middleware, I cant think of why its not working with prax.

Thanks in advance

TypeError: no implicit conversion of nil into String

/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:26:in `+'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:26:in `path'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:21:in `[]='
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:73:in `block in set_unviewed'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:69:in `synchronize'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/storage/file_store.rb:69:in `set_unviewed'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/rack-mini-profiler-0.1.31/Ruby/lib/mini_profiler/profiler.rb:325:in `call'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/engine.rb:511:in `call'
/home/bor/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/application.rb:97:in `call'
/home/bor/prax/lib/racker/handler.rb:24:in `call'
/home/bor/prax/lib/racker/handler.rb:16:in `handle_connection'
/home/bor/prax/lib/racker/server.rb:58:in `block (2 levels) in spawn_workers'
/home/bor/prax/lib/racker/server.rb:58:in `loop'
/home/bor/prax/lib/racker/server.rb:58:in `block in spawn_workers'
/home/bor/prax/lib/prax/workers.rb:30:in `call'
/home/bor/prax/lib/prax/workers.rb:30:in `block in spawn'