Rack ships with the Rack::RewindableInput::Middleware middleware for compatibility with older apps.

However, this middleware wraps rack.input unconditionally meaning that a nil input will also be wrapped potentially leading to exceptions.

Concretely, I have an older app with a middleware that's trying to req.body&.read and req.body&.rewind which for GET and HEAD requests now cause the following error:

NoMethodError: undefined method `read' for nil
   ~/.gem/ruby/3.3.6/gems/rack-3.1.8/lib/rack/rewindable_input.rb:96:in `make_rewindable'
   ~/.gem/ruby/3.3.6/gems/rack-3.1.8/lib/rack/rewindable_input.rb:41:in `read'

This middleware should probably interrogate req.request_method.

Even so, it seems that for backwards compatibility (and to avoid the possibility of runtime errors overall), it would be great to never wrap a nil value.