handle append from ui

src/jflow/workflow.py

@@ -195,8 +195,10 @@ class Workflow(threading.Thread):
             if args.has_key(param.name):
                 # if it's an append parameter, the result should be a list
                 if param.action == "append":
-                    try: value = args[param.name].split(",") 
-                    except: value = args[param.name]
+                    if args[param.name]:
+                        try: value = args[param.name].split(",") 
+                        except: value = args[param.name]
+                    else: value = []
                     extended_args[param.name] = value
                 # if it's a date
                 elif param.type == date: