printing more info for that weird CI error of resolver initialization

.rubocop-2.1.yml

@@ -23,3 +23,6 @@ Metrics/LineLength:
   Exclude:
     - 'test/resolver/native_test.rb'
   Max: 140
+
+Lint/UnneededCopDisableDirective:
+  Enabled: false

lib/httpx/pool.rb

@@ -161,7 +161,13 @@ module HTTPX
         resolver.on(:error, &method(:on_resolver_error))
         resolver.on(:close) { on_resolver_close(resolver) }
         resolver
+      # rubocop: disable Layout/RescueEnsureAlignment
+      rescue ArgumentError
+        # this block is here because of an error which happens on CI from time to time
+        warn "tried resolver: #{resolver_type}"
+        raise
       end
+      # rubocop: enable Layout/RescueEnsureAlignment
     end
   end
 end