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
@@ -187,15 +187,22 @@
     """
     if type(author_data) is dict:
         author_str = ""
-        if "name" in author_data:
-            author_str += author_data["name"]
-        if "email" in author_data:
-            author_str += " <%s>" % author_data["email"]
-        return author_str
+        name = author_data.get("name")
+        if name is not None:
+            if type(name) is str:
+                author_str += name
+            elif type(name) is list:
+                author_str += name[0] if len(name) > 0 else ""
+
+        email = author_data.get("email")
+        if email is not None:
+            author_str += f" <{email}>"
+        result = author_str
     elif type(author_data) is list:
-        return _author_str(author_data[0]) if len(author_data) > 0 else ""
+        result = _author_str(author_data[0]) if len(author_data) > 0 else ""
     else:
-        return author_data
+        result = author_data
+    return result
 
 
 def extract_npm_package_author(package_json) -> Person:
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
@@ -34,6 +34,11 @@
         ([], ""),
         ({"name": "groot", "email": "groot@galaxy.org",}, "groot <groot@galaxy.org>"),
         ({}, ""),
+        ({"name": []}, "",),
+        (
+            {"name": ["Susan McSween", "William H. Bonney", "Doc Scurlock",]},
+            "Susan McSween",
+        ),
     ]:
         assert _author_str(author) == expected_author