如何解析警告消息(未找到元数据对象;在扩展S4类的R包中没有导出的spatial allinesnull类)

This is my first question post on StackOverflow, so please correct any protocol errors I make. But I have already benefitted greatly from answers to many other questions on the site, so before I go further I would like to This is my first question post on StackOverflow