有什么办法可以解决R中的映射错误？

Question

b<-str_c(url,'&pageNumber=',seq(1,11,1))
b<-if_else(str_detect(b,"ie=UTF8&pageNumber=1")==TRUE,"https://www.amazon.com/Skin-Like-Mine-Kids/product-reviews/0997157984/ref=cm_cr_dp_d_show_all_btm?ie=UTF8&reviewerType=all_reviews",b)
b

get_reviews<-function(html_df){
  as.data.frame(
    read_html(html_df) %>%
      html_nodes(".review-text-content span")%>%
      html_text()

  )
}

data<-b %>%
  map(get_reviews)%>%
  bind_rows()

我正在接受亚马逊的评论。我试图把所有评论都写成一本书。在尝试使其映射后，出现了此错误。我该如何解决？

Unequal factor levels: coercing to character binding character and factor vector, coercing into character vector