Error from pyproject validation are unclear.

[SirMartin]

• I have searched the issue tracker and believe that this is not a duplicate.

Make sure you run commands with -v flag before pasting the output.

Steps to reproduce

I have an old project that contains a wrong field in the pyproject.toml. If you dig into the log file you can find the error, but the error message that PDM pops out to the console means almost nothing.

I tried to fix myself, but I cannot find a way to do it, I don´t have enough experience with python, or maybe the issue is in the PEP517 validator.

Actual behavior

Shows an unclear error message.

[BuildError]: Call command ['/usr/bin/python3.10', 
'/home/edu/.local/lib/python3.10/site-packages/pep517/in_process/_in_process.py'
, 'get_requires_for_build_editable', '/tmp/tmp3w36cbpv'] return non-zero 
status(1). Make sure the package is PEP 517-compliant, or you can add 
`--no-isolation` to the command.

Expected behavior

Shows the specific error.

pdm.pep517.exceptions.PEP621ValidationError: {'license-expression': ['unknown field']}

Environment Information

# Paste the output of `pdm info && pdm info --env` below:
PDM version:
  2.2.0
Python Interpreter:
  /usr/local/bin/python (3.9)
Project Root:
  /code
Project Packages:
  /code/__pypackages__/3.9

{
  "implementation_name": "cpython",
  "implementation_version": "3.9.7",
  "os_name": "posix",
  "platform_machine": "x86_64",
  "platform_release": "6.0.2-76060002-generic",
  "platform_system": "Linux",
  "platform_version": "#202210150739~1666289067~22.04~fe0ce53 SMP 
PREEMPT_DYNAMIC Thu O",
  "python_full_version": "3.9.7",
  "platform_python_implementation": "CPython",
  "python_version": "3.9",
  "sys_platform": "linux"
}

[frostming]

Can't you see the error with -v flag?

[SirMartin]

Yes I can, but could be more clear, is not critical but could be improved.