Crash when deb or rpm main archive source is not defined

[rezib]

When the source of a deb package is not provided in build request and not defined in artifact meta definition, fatbuildrd crashes with the following error:

fatbuildrd[614542]: worker-default: [INFO] fatbuildr.builds.formats.deb Building source Deb packages for slurm
fatbuildrd[614542]: Exception in thread worker-default:
fatbuildrd[614542]: Traceback (most recent call last):
fatbuildrd[614542]:   File "/usr/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
fatbuildrd[614542]:     self.run()
fatbuildrd[614542]:   File "/usr/lib/python3.10/threading.py", line 953, in run
fatbuildrd[614542]:     self._target(*self._args, **self._kwargs)
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/cli/fatbuildrd.py", line 133, in _worker
fatbuildrd[614542]:     instance.tasks_mgr.run(task)
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/tasks/manager.py", line 177, in run
fatbuildrd[614542]:     task.run()
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/builds/__init__.py", line 226, in run
fatbuildrd[614542]:     self.build()
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/builds/formats/deb.py", line 89, in build
fatbuildrd[614542]:     self._build_src()
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/builds/formats/deb.py", line 110, in _build_src
fatbuildrd[614542]:     main_tarball_subdir = extract_artifact_sources_archives(
fatbuildrd[614542]:   File "/usr/lib/python3/dist-packages/fatbuildr/utils.py", line 94, in extract_artifact_sources_archives
fatbuildrd[614542]:     main_archive.path,
fatbuildrd[614542]: AttributeError: 'NoneType' object has no attribute 'path'