🐛 fix(chains.py): set prompt field as required when value is None

The prompt field was previously set as not required when no value was provided, but this is not the intended behavior. The prompt field should always be required, even if the default prompt is used. This commit fixes the issue by setting the required attribute to True when the value is None.

src/backend/langflow/template/frontend_node/chains.py

@@ -21,8 +21,7 @@ class ChainFrontendNode(FrontendNode):
 
         # Separated for possible future changes
         if field.name == "prompt" and field.value is None:
-            # if no prompt is provided, use the default prompt
-            field.required = False
+            field.required = True
             field.show = True
             field.advanced = False
         if field.name == "memory":