Use early returns rather than large if in Variable#taint_check

lib/liquid/variable.rb

@@ -107,20 +107,21 @@ module Liquid
     end
 
     def taint_check(context, obj)
-      if obj.tainted? && Template.taint_mode != :lax
-        @markup =~ QuotedFragment
-        name = Regexp.last_match(0)
+      return unless obj.tainted?
+      return if Template.taint_mode == :lax
 
-        error = TaintedError.new("variable '#{name}' is tainted and was not escaped")
-        error.line_number = line_number
-        error.template_name = context.template_name
+      @markup =~ QuotedFragment
+      name = Regexp.last_match(0)
 
-        case Template.taint_mode
-        when :warn
-          context.warnings << error
-        when :error
-          raise error
-        end
+      error = TaintedError.new("variable '#{name}' is tainted and was not escaped")
+      error.line_number = line_number
+      error.template_name = context.template_name
+
+      case Template.taint_mode
+      when :warn
+        context.warnings << error
+      when :error
+        raise error
       end
     end
   end