若对话列表 contents 数组以 model 结尾，会报错： 
[
    ,
    [
        3,
        "[original: beyond::dependency::INVALID_ARGUMENT] Requests ending with a model turn are not supported unless the last part is a function response.",
        [
            [
                "type.googleapis.com/google.internal.alkali.applications.makersuite.v1.GeminiApiErrorDetails"
            ]
        ]
    ]
]

该功能在 3.5 flash 依然...