LangGraph nodes within Prompt Flow error out when Prompt Flow tracing is turned on

[yeamusic21]

Describe the bug
When using LangGraph within Prompt Flow, nodes that invoke a graph error out when Prompt Flow tracing is turned on.

How To Reproduce the bug
Steps to reproduce the behavior, how frequent can you experience the bug:

1. Create node that calls a LangGraph graph (graph.invoke(input))
2. Run Prompt Flow graph

Expected behavior
No error

Screenshots
N/A

Running Information(please complete the following information):

• Promptflow Package Version: promptflow==1.16.1
• Operating System: Windows 11
• Python Version: 3.13.0

Additional context
Running graph.invoke(input) works when setting PF_DISABLE_TRACING=true

Without setting this env variable, we get the following message:

File **"C:\Users\MattY\Code\PromptFlowSandbox\PrmtFlPyVenv\Lib\site-packages\promptflow\tracing\_trace.py"**, line 145, in collect_openai_tokens_for_parent_span
    **key: (self._span_id_to_tokens[parent_span_id].get(key, 0) or 0) + (tokens.get(key, 0) or 0)**
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
TypeError: unsupported operand type(s) for +: 'dict' and 'dict'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\MattY\Code\PromptFlowSandbox\PrmtFlPyVenv\Lib\site-packages\promptflow\_core\flow_execution_context.py", line 90, in invoke_tool
    result = self._invoke_tool_inner(node, f, kwargs)
  File "C:\Users\MattY\Code\PromptFlowSandbox\PrmtFlPyVenv\Lib\site-packages\promptflow\_core\flow_execution_context.py", line 206, in _invoke_tool_inner
    raise ToolExecutionError(node_name=node_name, module=module) from e
promptflow._core._errors.ToolExecutionError: Execution failure in 'python_concat': (TypeError) unsupported operand type(s) for +: 'dict' and 'dict'
2024-11-11 14:29:39 -0500    8824 execution.flow     WARNING  Failed to calculate metrics due to exception: unsupported operand type(s) for +: 'int' and 'dict'.
2024-11-11 14:29:39 -0500    8824 execution.flow     WARNING  Failed to calculate metrics due to exception: unsupported operand type(s) for +: 'int' and 'dict'.
2024-11-11 14:29:39 -0500    8824 execution.flow     ERROR    Flow execution has failed. Cancelling all running nodes: python_concat.
pf.flow.test failed with UserErrorException: TypeError: **Execution failure in 'python_concat': (TypeError) unsupported operand type(s) for +: 'dict' and 'dict'**
WARNING:azure.monitor.opentelemetry.exporter.export._base:Retrying due to server request error: <urllib3.connection.HTTPSConnection object at 0x000001EE56BA7ED0>: Failed to resolve 'eastus-8.in.applicationinsights.azure.com' ([Errno 11001] getaddrinfo failed).

[github-actions]

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[yeamusic21]

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