changes

app/workflow_utils.py

@@ -45,8 +45,8 @@ def resolve_value(expr, context):
         arg2_val = resolve_value(func_match.group(3).strip(), context)
 
         try:
-            num1 = float(arg1_val) if arg1_val is not None else 0
-            num2 = float(arg2_val) if arg2_val is not None else 0
+            num1 = float(arg1_val or 0)
+            num2 = float(arg2_val or 0)
             if func_name == "add":
                 return num1 + num2
             if func_name == "sub":