当我试图通过Rstudio中的编译报告功能将R文件转换为R markdown文件时，我遇到了这个错误消息，我不明白为什么。

processing file: airline_customerSatisfaction.spin.Rmd
  |.......................                                               |  33%
  ordinary text without R code

  |...............................................                       |  67%
label: unnamed-chunk-1

Quitting from lines 3-346 (airline_customerSatisfaction.spin.Rmd) 
Error in contrib.url(repos, "source") : 
  trying to use CRAN without setting a mirror
Calls: <Anonymous> ... eval_with_user_handlers -> eval -> eval -> install.packages -> contrib.url
In addition: Warning message:
In do_once((if (is_R_CMD_check()) stop else warning)("The function xfun::isFALSE() will be deprecated in the future. Please ",  :
  The function xfun::isFALSE() will be deprecated in the future. Please consider using base::isFALSE(x) or identical(x, FALSE) instead.
Execution halted

有人能给我解释一下为什么会发生这种情况吗？谢谢！