Error analysis fails when PDL doesn't match schema

[vite-falcon]

Summary

When the PDL doesn't match the schema, the error analysis fails as it attempts to retrieve the field names without verifying that "properties" key exists in ref_type.

Sample PDL

description: Vision model example
text:
- model: openai/gpt-4o-mini
  input:
    array:
    - role: user
      content:
      - type: text
        text: "What's in this image?"
      - type: image_url
        image_url:
          url: "https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Gfp-wisconsin-madison-the-nature-boardwalk.jpg/2560px-Gfp-wisconsin-madison-the-nature-boardwalk.jpg"
  parameters:
    max_tokens: 500
    temperature: 0.7

Expected Error

['from-string:8 - [{\'type\': \'text\', \'text\': "What\'s in this image?"}, {\'type\': \'image_url\', \'image_url\': {\'url\': \'https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Gfp-wisconsin-madison-the-nature-boardwalk.jpg/2560px-Gfp-wisconsin-madison-the-nature-boardwalk.jpg\'}}] should not be a list'].

Actual Error

'properties' 

File "[...]\noxfile.py", line 85, in pdl_lint
    PdlExecutor.validate_pdl_file(pdl_file)
  File "[...]\pdl\executor.py", line 192, in validate_pdl_file
    PdlExecutor.validate_pdl_string(pdl_file.read_text(encoding="utf-8"))
  File "[...]\pdl\executor.py", line 185, in validate_pdl_string
    _, _ = parse_pdl_str(pdl_string, file_name=file_name)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_parser.py", line 39, in parse_str
    errors = analyze_errors(defs, defs["Program"], prog_yaml, loc)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 188, in analyze_errors
    ret += analyze_errors(defs, match_ref, data, loc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 117, in analyze_errors
    ret += analyze_errors(
           ^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 157, in analyze_errors
    ret += analyze_errors(defs, found, data, loc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 91, in analyze_errors
    ret += analyze_errors(defs, schema["items"], item, newloc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 188, in analyze_errors
    ret += analyze_errors(defs, match_ref, data, loc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 117, in analyze_errors
    ret += analyze_errors(
           ^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 167, in analyze_errors
    field_matches = match(item, data)
                    ^^^^^^^^^^^^^^^^^
  File "[...]\.venv\Lib\site-packages\pdl\pdl_schema_error_analyzer.py", line 51, in match
    all_fields = ref_type["properties"].keys()
                 ~~~~~~~~^^^^^^^^^^^^^^

Proposal

The fix that seems to work is to change line 51 in pdl_schema_error_analyzer.py to:

all_fields = ref_type.get("properties", {}).keys()