fixed type error for all version

Author: CodingSamrat

filexdb/collection.py

@@ -383,9 +383,9 @@ def _doc_is_exists(self, doc_id: str) -> bool:
 
         return False
 
-    def _find_document_by_id(self, doc_id) -> Document | str:
+    def _find_document_by_id(self, doc_id) -> Document:
         for doc in self._collection:
             if doc["_id_"] == doc_id:
                 return doc
             else:
-                return "none"
+                return None