Handle None __str__

app/models.py

@@ -665,7 +665,7 @@ Involved scientist''')
         return " ".join([self.title, self.first_name, self.last_name])
 
     def __str__(self):
-        return self.fullname()
+        return self.fullname() if self.fullname() else ""
 
     def dict(self):
         return {