fix undefined method 'field_value'

config/initializers/hexapdf.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# fix NoMethodError: undefined method `field_value' for #<HexaPDF::Type::AcroForm::Field
+module HexaPDF
+  module Type
+    module AcroForm
+      class Field
+        def field_value
+          ''
+        end
+      end
+    end
+  end
+end