Unexpected config error when a default config file is empty

[victor-yon]

🐛 Bug report

If at least one default_config_files is set and this file is empty, a TypeError: Unexpected config: is triggered on parser.parse_args(). Even if no argument is mandatory.

To reproduce

from jsonargparse import ArgumentParser

parser = ArgumentParser(default_config_files=['config.yaml'])
parser.add_argument("test", type=int, help="test", default=1)
cfg = parser.parse_args()
print(cfg.as_dict())

no 'config.yaml' file

python main.py
> {'test': 1}

Work as expected, no error

empty 'config.yaml' file

touch config.yaml
python main.py
> Unexpected config error:

Not empty 'config.yaml' file
Work as expected, no error

echo "test: 42" > config.yaml
python bug.py
> {'test': 42, '__default_config__': Path_fr(config.yaml, cwd=/Users/...)}

Expected behavior

I expect to have the same behavior between no configuration file and empty configuration file.
In the case where every argument are optional I don't expect to have an error.

In my case I wanted to generate this default configuration file as suggest in the document with:

python example.py --print_config > config.yaml

But an empty file is created before to run the script. Which trigger the issue mentioned above.

Environment

• jsonargparse version: 4.24.0
• Python version: 3.11.4
• How jsonargparse was installed: pip install jsonargparse[signatures]~=4.24 docstring-parser~=0.15 PyYAML~=6.0 ruyaml~=0.91
• OS: macOS 13.4.1

[mauvilsa]

@victor-yon thank you for reporting!

You are right. The recommended steps to create a config should not fail just because default_config_files is used. This should be fixed.

[mauvilsa]

@victor-yon I created pull request #370 fixing this. Please try it out.

[victor-yon]

Hi, thank you for the fix. I can try next Monday, I don't have access to my computer before.

[mauvilsa]

Merged it since I wanted to create a release and this change was simple. You can test it next week with the released package. If there are issues, please comment here.

[victor-yon]

I confirm that is working as expected with jsonargparse v4.24.1. Thank you.