fix infinite loop

config/initializers/hexapdf.rb

@@ -124,6 +124,38 @@ module HexaPDF
     end
   end
 
+  module CycleSafeEachField
+    def each_field(terminal_only: true)
+      return to_enum(__method__, terminal_only:) unless block_given?
+
+      seen = Set.new.compare_by_identity
+
+      process_field_array = lambda do |array|
+        array.each_with_index do |field, index|
+          next if field.nil?
+
+          unless field.respond_to?(:type) && field.type == :XXAcroFormField
+            array[index] = field = HexaPDF::Type::AcroForm::Field.wrap(document, field)
+          end
+
+          next unless seen.add?(field.value)
+
+          if field.terminal_field?
+            yield(field)
+          else
+            yield(field) unless terminal_only
+
+            process_field_array.call(field[:Kids])
+          end
+        end
+      end
+
+      process_field_array.call(root_fields)
+
+      self
+    end
+  end
+
   module CycleSafeFullFieldName
     def full_field_name(seen = Set.new.compare_by_identity)
       return field_name unless seen.add?(value)
@@ -139,3 +171,4 @@ end
 
 HexaPDF::Type::AcroForm::Field.singleton_class.prepend(HexaPDF::CycleSafeInheritedValue)
 HexaPDF::Type::AcroForm::Field.prepend(HexaPDF::CycleSafeFullFieldName)
+HexaPDF::Type::AcroForm::Form.prepend(HexaPDF::CycleSafeEachField)