🐛 fix(loading.py): handle case when "handle_keys" is not in params dictionary and add input_variable to "handle_keys" list

The code now checks if the "handle_keys" key is present in the params dictionary. If it is not present, it creates an empty list and adds the input_variable to it. This ensures that the "handle_keys" list is always present and the input_variable is correctly added to it.

src/backend/langflow/interface/initialize/loading.py

@@ -142,6 +142,13 @@ def instantiate_prompt(node_type, class_object, params):
                         for item in variable
                     ]
                 )
+                # handle_keys will be a list but it does not exist yet
+                # so we need to create it
+                if "handle_keys" not in params:
+                    format_kwargs["handle_keys"] = []
+
+                # Add the handle_keys to the list
+                format_kwargs["handle_keys"].append(input_variable)
 
     return prompt, format_kwargs