spec-parser run reports errors but exits with 0 #80
Description
The current spec parser reports an error but does still exit with EXIT_SUCCESS. See for example https://github.com/spdx/spdx-3-model/actions/runs/7118823989/job/19382571564#step:5:25 with the log:
> Run cd spec-parser
WARNING : External property restrictions aren't yet handled properly, they are added to the description of the class.
WARNING : skipping ../model/Core/Properties/_property.md
WARNING : skipping ../model/Core/Vocabularies/_vocab.md
WARNING : External property restrictions aren't yet handled properly, they are added to the description of the class.
WARNING : External property restrictions aren't yet handled properly, they are added to the description of the class.
WARNING : External property restrictions aren't yet handled properly, they are added to the description of the class.
WARNING : External property restrictions aren't yet handled properly, they are added to the description of the class.
WARNING : Overwriting out_dir `/tmp/spec-parser.out`
ERROR : Invalid Nature attribute in metadata `None`