Function deserializeStoredGeneration

Returns
    | {
        message: | HumanMessage<MessageStructure>
        | AIMessage<MessageStructure>
        | SystemMessage<MessageStructure>
        | FunctionMessage<MessageStructure>
        | ToolMessage<MessageStructure>
        | ChatMessage<MessageStructure>;
        text: string;
    }
    | { message?: undefined; text: string }