Raise an exception if there's no package name in metadata

That's an error state that can't be allowed to proceed further.

pyp2spec/utils.py

@@ -26,10 +26,16 @@ class SdistNotFoundError(Pyp2specError):
     """Raised when there's no sdist file in the PyPI metadata"""
 
 
+class MissingPackageNameError(Pyp2specError):
+    """Raised when there's no package name in the metadata"""
+
+
 def normalize_name(package_name: str) -> str:
     """Normalize given package name as defined in PEP 503.
     The resulting string better conforms with Fedora's Packaging Guidelines."""
 
+    if not package_name:
+        raise MissingPackageNameError("Cannot create a package without a name")
     return re.sub(r"[-_.]+", "-", package_name).lower()
 
 

tests/test_utils.py

@@ -3,7 +3,7 @@ import pytest
 from pyp2spec.utils import filter_license_classifiers, prepend_name_with_python
 from pyp2spec.utils import normalize_name, get_extras, is_archful
 from pyp2spec.utils import normalize_as_wheel_name, archive_name
-from pyp2spec.utils import resolve_url, SdistNotFoundError
+from pyp2spec.utils import resolve_url, SdistNotFoundError, MissingPackageNameError
 
 
 def test_license_classifier_read_correctly():
@@ -122,13 +122,17 @@ def test_archfulness_is_detected_from_multiple_urls_3():
         ("my.package", "my_package"),
         ("my_package-", "my_package_"),
         ("noweirdchars", "noweirdchars"),
-        ("", ""),
     ]
 )
 def test_normalize_as_wheel_name(name, expected):
     assert normalize_as_wheel_name(name) == expected
 
 
+def test_empty_package_name_results_in_exception():
+    with pytest.raises(MissingPackageNameError):
+        normalize_as_wheel_name("")
+
+
 def test_archive_name_valid():
     archive_urls = [
         {