Remove more dead code

Author: byroot

CHANGES.md

@@ -10,6 +10,8 @@
 * Remove deprecated `JSON.unparse` method.
 * Remove deprecated `JSON.fast_unparse` method.
 * Remove deprecated `JSON.pretty_unparse` method.
+* Remove deprecated `JSON::UnparserError` constant.
+* Remove outdated `JSON::MissingUnicodeSupport` constant.
 
 ### 2025-03-12 (2.10.2)
 

lib/json/common.rb

@@ -161,13 +161,6 @@ def detailed_message(...)
     end
   end
 
-  # For backwards compatibility
-  UnparserError = GeneratorError # :nodoc:
-
-  # This exception is raised if the required unicode support is missing on the
-  # system. Usually this means that the iconv library is not installed.
-  class MissingUnicodeSupport < JSONError; end
-
   # Fragment of JSON document that is to be included as is:
   #   fragment = JSON::Fragment.new("[1, 2, 3]")
   #   JSON.generate({ count: 3, items: fragments })