Extract rescue code from BlockBody#render_node for re-use in liquid-c

lib/liquid/block_body.rb

@@ -71,17 +71,25 @@ module Liquid
     # @api private
     def self.render_node(context, output, node)
       node.render_to_output_buffer(context, output)
-    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
+    rescue => exc
-      context.handle_error(e, node.line_number)
+      blank_tag = !node.instance_of?(Variable) && node.blank?
-    rescue MemoryError
+      rescue_render_node(context, output, node.line_number, exc, blank_tag)
+    end
+
+    # @api private
+    def self.rescue_render_node(context, output, line_number, exc, blank_tag)
+      case exc
+      when MemoryError
         raise
-    rescue ::StandardError => e
+      when UndefinedVariable, UndefinedDropMethod, UndefinedFilter
-      line_number = node.is_a?(String) ? nil : node.line_number
+        context.handle_error(exc, line_number)
-      error_message = context.handle_error(e, line_number)
+      else
-      if node.instance_of?(Variable) || !node.blank? # conditional for backwards compatibility
+        error_message = context.handle_error(exc, line_number)
+        unless blank_tag # conditional for backwards compatibility
           output << error_message
         end
       end
+    end
 
     private def parse_liquid_tag(markup, parse_context)
       liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)