Hatchling v1.26.1 not allow string-value to license key in pyproject.toml

[digitronik]

I am encountering an error when setting the license field to an string-value (license = "something") in the pyproject.toml file, using Hatchling v1.26.1.

[project]
name = "foo-bar"
readme = "README.rst"
license = "MIT OR GPL-2.0-or-later OR (FSFUL AND BSD-2-Clause)"

I think as per PEP 639, setting the license field to an string is completely valid. However, Hatchling is throwing the following error during the build process:

  Preparing editable metadata (pyproject.toml) ... error
  error: subprocess-exited-with-error
  
  × Preparing editable metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [21 lines of output]
      Traceback (most recent call last):
        File "/home/ndhandre/RedHat/iqe/.iqe_env/lib64/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 353, in <module>
          main()
        File "/home/ndhandre/RedHat/iqe/.iqe_env/lib64/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 335, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/home/ndhandre/RedHat/iqe/.iqe_env/lib64/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 176, in prepare_metadata_for_build_editable
          whl_basename = build_hook(metadata_directory, config_settings)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/tmp/pip-build-env-exmmg97_/overlay/lib/python3.11/site-packages/hatchling/build.py", line 83, in build_editable
          return os.path.basename(next(builder.build(directory=wheel_directory, versions=['editable'])))
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/tmp/pip-build-env-exmmg97_/overlay/lib/python3.11/site-packages/hatchling/builders/plugin/interface.py", line 90, in build
          self.metadata.validate_fields()
        File "/tmp/pip-build-env-exmmg97_/overlay/lib/python3.11/site-packages/hatchling/metadata/core.py", line 266, in validate_fields
          self.core.validate_fields()
        File "/tmp/pip-build-env-exmmg97_/overlay/lib/python3.11/site-packages/hatchling/metadata/core.py", line 1366, in validate_fields
          getattr(self, attribute)
        File "/tmp/pip-build-env-exmmg97_/overlay/lib/python3.11/site-packages/hatchling/metadata/core.py", line 683, in license
          raise ValueError(message) from None
      ValueError: Error parsing field `project.license` - Invalid license expression: ''
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

[ofek]

Please show me something so that I can reproduce, I can't from your example.