diff --git a/swh/loader/package/npm/loader.py b/swh/loader/package/npm/loader.py
--- a/swh/loader/package/npm/loader.py
+++ b/swh/loader/package/npm/loader.py
@@ -29,6 +29,9 @@
 logger = logging.getLogger(__name__)
 
 
+EMPTY_PERSON = Person(fullname=b"", name=None, email=None)
+
+
 class NpmLoader(PackageLoader):
     """Load npm origin's artifact releases into swh archive.
 
@@ -210,7 +213,7 @@
     return it in swh format.
 
     Args:
-        package_json (dict): Dict holding the content of parsed
+        package_json: Dict holding the content of parsed
             ``package.json`` file
 
     Returns:
@@ -219,10 +222,13 @@
     """
     for author_key in ("author", "authors"):
         if author_key in package_json:
-            author_str = _author_str(package_json[author_key])
+            author_data = package_json[author_key]
+            if author_data is None:
+                return EMPTY_PERSON
+            author_str = _author_str(author_data)
             return Person.from_fullname(author_str.encode())
 
-    return Person(fullname=b"", name=None, email=None)
+    return EMPTY_PERSON
 
 
 def _lstrip_bom(s, bom=BOM_UTF8):
diff --git a/swh/loader/package/npm/tests/test_npm.py b/swh/loader/package/npm/tests/test_npm.py
--- a/swh/loader/package/npm/tests/test_npm.py
+++ b/swh/loader/package/npm/tests/test_npm.py
@@ -46,6 +46,7 @@
             {"name": ["Susan McSween", "William H. Bonney", "Doc Scurlock",]},
             "Susan McSween",
         ),
+        (None, None),
     ]:
         assert _author_str(author) == expected_author
 
@@ -190,6 +191,17 @@
         email=b"448627663@qq.com",
     )
 
+    package_json_no_authors = json.loads(
+        """{
+        "authors": null,
+        "license": "MIT"
+    }"""
+    )
+
+    assert extract_npm_package_author(package_json_no_authors) == Person(
+        fullname=b"", name=None, email=None
+    )
+
 
 def normalize_hashes(hashes):
     if isinstance(hashes, str):