为何try-except Exception未生效？输入非X/Y时无异常触发

你的代码里的try-except逻辑完全无效：

• 当前try块里的if/elif判断根本不会触发FileNotFoundError，所以当传入的type_of_model既不是X也不是Y时，代码会直接跳过整个try-except结构，不会进入except分支抛异常。
• 而且你捕获的FileNotFoundError和参数不匹配的场景完全不沾边，属于用错了异常类型。

直接去掉多余的try-except，在参数不符合要求时主动抛出异常就行：

def preprocess_corresponds_to_model(type_of_model: str) -> function:
    if type_of_model == "X":
        return preprocess_location_df
    elif type_of_model == "Y":
        return preprocess_event_df
    else:
        raise ValueError(
            f"The model {type_of_model} does not exist. "
            "The model should be either X or Y"
        )

如果非要保留try-except结构（其实没必要，属于画蛇添足），可以改成这样：

def preprocess_corresponds_to_model(type_of_model: str) -> function:
    try:
        if type_of_model == "X":
            return preprocess_location_df
        elif type_of_model == "Y":
            return preprocess_event_df
        # 不符合条件时主动触发异常
        raise ValueError(f"Invalid model type: {type_of_model}")
    except ValueError as exception:
        raise Exception(
            f"The model {type_of_model} does not exist. "
            "The model should be either X or Y"
        ) from exception

内容的提问来源于stack exchange，提问作者Ololo