Error running a SignatureOptimizer

[cemkod]

I am trying to run a signature optimizer and getting the following error:

Exception has occurred: AttributeError       (note: full exception trace is shown but execution is paused at: _run_module_as_main)
'str' object has no attribute 'items'
  File "D:\CodeBase\Researcher\.venv\Lib\site-packages\dspy\evaluate\evaluate.py", line 239, in merge_dicts
    for k, v in d2.items():
                ^^^^^^^^
  File "D:\CodeBase\Researcher\.venv\Lib\site-packages\dspy\evaluate\evaluate.py", line 181, in __call__
    merge_dicts(example, prediction) | {"correct": score} for _, example, prediction, score in predicted_devset
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\CodeBase\Researcher\.venv\Lib\site-packages\dspy\teleprompt\copro_optimizer.py", line 182, in compile
    score = evaluate(module_clone, devset=trainset, **eval_kwargs)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\CodeBase\Researcher\.venv\Lib\site-packages\dspy\teleprompt\signature_opt.py", line 41, in compile
    return super().compile(student, trainset=devset, eval_kwargs=eval_kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\CodeBase\Researcher\concept_iterator_optimizer.py", line 96, in <module>
    optimized_program = teleprompter.compile(student=ConceptFinder(), devset=input_data,eval_kwargs=kwargs)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Python\Lib\runpy.py", line 88, in _run_code
    exec(code, run_globals)
  File "D:\Python\Lib\runpy.py", line 198, in _run_module_as_main (Current frame)
    return _run_code(code, main_globals, None,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'str' object has no attribute 'items'

What I'm trying to do is optimizing the Prompts for a related concept generator, given a subject.
I have included the full source and my devset file (it is quite small). Can't seem to find what is wrong with it. Am I running against a bug, or is it something stupid I'm doing?
Researcher.zip

[cemkod]

For anyone having a similar issue: My evaluator was broken. I tested the evaluator seperately and fixed it. now it works.