关于逗号+and的问题

洋果子店

e.g.we decided not to eat at the restaurant, and instead to cook our own food at home.

e.g…believes that the economy will avoid the recession, but rather come to a soft landing.

这两个句子中逗号+and，but后面是否应该补充出完整主谓，或者去掉逗号（但是觉得怪怪的）

这样的句子可以判断为有效性错误吗