In MAKE-NUMBER-INPUT-FIELD set default value field only if default

text is given.

scheme/httpd/surflets/surflets.scm

@@ -369,12 +369,12 @@
 	    ((default (lambda (a) (or (number? a)
 				      (string-or-symbol? a))))
 	     (attributes XML-attribute?))
-	  (make-input-field 
+	  (make-input-field
 	   name
 	   number-input-field-transformer
 	   `(input (@ (type "text")
 		      (name ,name)
-		      (value ,default)
+		      ,(and default `(value ,default))
 		      ,(and attributes (cdr attributes))))))))))
 
 (define (make-password-input-field . maybe-further-attributes)