Add handling for config directory with .yml/.yaml extension

[winstonallo]

Description

Prevents a (probably mistakenly created) config.yml/ directory from being attempted to open as a regular file, resulting in a misleading PermissionError (source: just happened to me).

Before: PermissionError: [Errno 13] Permission denied: 'config.yml'
After: config.yml/ directory is treated as a valid config directory (falls through to existing directory handling logic).

[trebedea]

Looks good! Nice catch 👍

[Copilot]

Pull Request Overview

This PR fixes an issue where a directory with a .yml or .yaml extension would be incorrectly treated as a configuration file, causing a misleading PermissionError when attempting to open it. The fix adds an explicit file check to ensure only actual files with these extensions are processed as YAML config files, while directories fall through to the existing directory handling logic.

• Added os.path.isfile() check to prevent directories with YAML extensions from being treated as config files
• Maintains existing functionality for actual YAML config files
• Improves error handling and user experience when config directories are mistakenly created with YAML extensions

[Pouyanpi]

@winstonallo thanks! would you please run the pre-commits per the contributing guideline.

Also this PR misses a regression test covering the directory with yml extension scenario

so a test case like:

def test_yaml_directory_handling():
    # like create a directory named whatever_config.yml
    # verify it's handled as a directory, not a file

this test should fail on the develop branch prior to this PR and go green afterwards.

[winstonallo]

Hey, sorry for the late response, I will get to that on Wednesday:)

[winstonallo]

Hey @Pouyanpi, I added the test and ran the pre-commit hooks:) Let me know if there is anything else I can do

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.20%. Comparing base (cd14a07) to head (90cd8e1).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1293   +/-   ##
========================================
  Coverage    70.20%   70.20%           
========================================
  Files          161      161           
  Lines        16123    16123           
========================================
  Hits         11319    11319           
  Misses        4804     4804           

Flag	Coverage Δ
python	70.20% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
nemoguardrails/rails/llm/config.py	90.32% <100.00%> (ø)

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