TypeError("Invalid message type: <class 'str'>. Expected dict or Pydantic model.")

[esnible]

Describe the bug
A seemingly valid PDL program produces

notools.pdl:2 - Error during 'ollama/granite-code:8b' model call: TypeError("Invalid message type: <class 'str'>. Expected dict or Pydantic model.")

If run with Open Telemetry support, produces the above, plus opentelemetry.py:651 - OpenTelemetry logging error in set_attributes 'str' object has no attribute 'get', plus a backtrace.

To Reproduce
Use pdl notools.pdl with the program

text:
- model: ollama/granite-code:8b
  input:
    array:
    - role: user
      content: What's the current weather in New York?
    - role: assistant
      # If I don't define this, I get "Invalid message type: <class 'str'>. Expected dict or Pydantic model."
      # content: ""

Expected behavior
An LLM response regarding weather

Desktop (please complete the following information):

• OS: MacOS
• Version commit d1df52d

Additional context
Uncommenting the content line in the example fixes the problem, yielding an expected hallucination:

assistant: The current weather in New York is sunny with a high of 72 degrees. The air pressure is 1023 mb, and the wind speed is 6 mph from the southwest. There is a 25% chance of rain.

[vazirim]

@esnible Thanks for reporting, but without the content field the message is ill-formed. That error message comes from ollama, not PDL (there should be an error).

[esnible]

I am using the PDL Schemas in VSCode, but no error is displayed, which caused me to think the program was valid.

I am not suggesting my PDL progam is correct. I am suggesting that the error, "Expected dict or Pydantic model" is difficult to understand. I am left confused about which PDL entity should be changed from string to dict or Pydantic model.

I don't know if it makes a difference, but I stumbled across this looking at https://www.ibm.com/granite/docs/models/granite/#granite-3.1-highlights . It showed a prompt that seemed to end with empty assistant response. I have another variant PDL program that lists tools, and I was using it to test how Granite produces tool calling.