Javascript NodeEmailer href附件会被调用两次

当我在“附件”中使用对象数组时，NodeEmailer会调用两次hrefs

例如：

    message: {
        from: process.env.QUOTATIONS_EMAIL_ACCOUNT,
        attachments: [{href: process.env.SERVER + '/api/v1/files/58a9cabd0d1acd471642d000bd23c0f7'}]
    },

“/api/v1/files/58a9cabd0d1acd471642d000bd23c0f7”：

结果：

called for: 58a9cabd0d1acd471642d000bd23c0f7
called for: 58a9cabd0d1acd471642d000bd23c0f7

看起来对象的数量是相乘的两倍

如果我将使用单个对象而不是对象数组：

    message: {
        from: process.env.QUOTATIONS_EMAIL_ACCOUNT,
        attachments: {href: process.env.SERVER + '/api/v1/files/58a9cabd0d1acd471642d000bd23c0f7'}
    },

它只会被调用一次

    message: {
        from: process.env.QUOTATIONS_EMAIL_ACCOUNT,
        attachments: {href: process.env.SERVER + '/api/v1/files/58a9cabd0d1acd471642d000bd23c0f7'}
    },