Catch 'Error in reactor loop escaped: mode not supported for this object: r' (#2477)

The following error happens intermittently in non MRI CI:

Error in reactor loop escaped: mode not supported for this object: r (ArgumentError)

Add rescue in `Reactor#register

History.md

@@ -10,6 +10,7 @@
 
 * Bugfixes
   * Your bugfix goes here <Most recent on the top, like GitHub> (#Github Number)
+  * Catch 'Error in reactor loop escaped: mode not supported for this object: r' (#2477)
   * Ignore Rails' reaper thread (and any thread marked forksafe) for warning ([#2475])
   * Ignore illegal (by Rack spec) response header ([#2439])
   * Close idle connections immediately on shutdown ([#2460])

lib/puma/reactor.rb

@@ -95,6 +95,8 @@ module Puma
     def register(client)
       @selector.register(client.to_io, :r).value = client
       @timeouts << client
+    rescue ArgumentError
+      # unreadable clients raise error when processed by NIO
     end
 
     # 'Wake up' a monitored object by calling the provided block.