Do not permit empty python namespace names

tests/unit/core/python/namespaces/test_PythonModuleNamespace.py

@@ -4,11 +4,9 @@ import pytest
 class StrSubclass(str): ...
 
 @pytest.mark.parametrize('namespace,expected_name', [
-    (PythonModuleNamespace(''), ''),
-    (PythonModuleNamespace(' '), ' '),
     (PythonModuleNamespace('a'), 'a'),
     (PythonModuleNamespace('1'), '1'),
-    (PythonModuleNamespace(StrSubclass('')), StrSubclass('')),
+    (PythonModuleNamespace(StrSubclass('a')), StrSubclass('a')),
 ])
 def test_PythonModuleNamespace_name_attribute(namespace, expected_name):
     assert namespace.name == expected_name

tests/unit/core/python/namespaces/test_PythonNamespace.py

@@ -4,11 +4,9 @@ import pytest
 class StrSubclass(str): ...
 
 @pytest.mark.parametrize('namespace,expected_name', [
-    (PythonNamespace(''), ''),
-    (PythonNamespace(' '), ' '),
     (PythonNamespace('a'), 'a'),
     (PythonNamespace('1'), '1'),
-    (PythonNamespace(StrSubclass('')), StrSubclass('')),
+    (PythonNamespace(StrSubclass('a')), StrSubclass('a')),
 ])
 def test_PythonNamespace_name_attribute(namespace, expected_name):
     assert namespace.name == expected_name