Puma and rack-timeout results in a null pointer after running for some time

We recently tried introducing request timeouts for our Rails application using this gem. While this setup works for some time, we run into a null pointer exception at some point:

NoMethodError: undefined method `state=' for nil:NilClass
  _set_state! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/core.rb:193
  call at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/core.rb:123
  call at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/core.rb:125
  run! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:39
  run! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:52
  run_loop! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:100
  each at org/jruby/RubyArray.java:1865
  run_loop! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:100
  loop at org/jruby/RubyKernel.java:1507
  run_loop! at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:81
  runner at /usr/local/bundle/gems/rack-timeout-0.6.3/lib/rack/timeout/support/scheduler.rb:73

So it appears that the env either no longer holds the state or never held it in the first place.

Our setup is as follows:

• JRuby 9.3.4.0
• Rails 6.1.7.2
• Puma 6.2.1

Any help would be very much appreciated

Start by tracing _set_state! and call in lib/rack/timeout/core.rb, then follow the scheduler flow in lib/rack/timeout/support/scheduler.rb. Reproduce the failure with the reported JRuby, Rails, Puma, and rack-timeout versions, and determine why the request environment lacks the expected state. Done means the null-state path is understood and the timeout flow no longer raises this exception.