Use parse_context or options instead of @options.

lib/liquid/parser_switching.rb

@@ -1,14 +1,14 @@
 module Liquid
   module ParserSwitching
     def parse_with_selected_parser(markup)
-      case @options.error_mode
+      case parse_context.error_mode
       when :strict then strict_parse_with_error_context(markup)
       when :lax    then lax_parse(markup)
       when :warn
         begin
           return strict_parse_with_error_context(markup)
         rescue SyntaxError => e
-          @options.warnings << e
+          parse_context.warnings << e
           return lax_parse(markup)
         end
       end