Add is_initialized() method to the MongoDB class

This is to ensure that we are calling `MongoDB.close()` only if the client has been properly initialized.

trolldb/database/mongodb.py

@@ -180,6 +180,11 @@ async def initialize(cls, database_config: DatabaseConfig):
         cls.__main_collection = cls.__main_database.get_collection(database_config.main_collection_name)
         logger.info("MongoDB is successfully initialized.")
 
+    @classmethod
+    def is_initialized(cls) -> bool:
+        """Checks if the motor client is initialized."""
+        return cls.__client is not None
+
     @classmethod
     def close(cls) -> None:
         """Closes the motor client."""
@@ -308,5 +313,8 @@ async def mongodb_context(database_config: DatabaseConfig) -> AsyncGenerator:
         await MongoDB.initialize(database_config)
         yield
     finally:
-        MongoDB.close()
+        if MongoDB.is_initialized():
+            MongoDB.close()
+        else:
+            logger.info("The MongoDB client was not initialized!")
         logger.info("The MongoDB context manager is successfully closed.")