refactor lookup_user

Author: aaruni96

etc/update-contributors.py

@@ -76,20 +76,21 @@ def norm_name(s: str) -> str:
     return s.casefold()
 
 
-def lookup_user(gh, email, name):
-    user = (
-        (gh and name_owner.get(norm_name(gh))) or
-        (email and email_owner.get(email.casefold())) or
-        name_owner.get(norm_name(name))
-    )
+def lookup_user(gh_username: str, email: str, name: str) ->  dict | None:
+    if gh_username:
+        user = name_owner.get(norm_name(gh_username))
+    elif email:
+        user = email_owner.get(email.casefold())
+    else:
+        user = name_owner.get(norm_name(name))
     return user
 
 # helpers to find co authors
 
 
-def find_author_github_nick(email: str, repos: list[str]) -> str | None:
+def find_author_github_nick(email: str, repos: list[str]) -> str:
     if not email:
-        return None
+        return ""
     for r in repos:
         commit_hash = git_out(
             repo_dir(r),
@@ -109,7 +110,7 @@ def find_author_github_nick(email: str, repos: list[str]) -> str | None:
         author = resp.json().get("author")
         if author and author.get("login"):
             return author["login"]
-    return None
+    return ""
 
 
 def find_coauthor_commit(name: str, email: str, repos: list[str]) -> str: