RedditExtractoR in R language: error-Subscript out of bounds

Question

My goal is to use RedditExtractoR to crawl reddit user post. The following is my code:

library(tidyverse)
library(RedditExtractoR)
user <- "a_guy828"
user_content <- get_user_content(user) # It shows error that page[[content_type]]：subscript out of bounds
user_threads<-user_content[[user]]$threads
view(user_threads)

When working in user_content <- get_user_content(user) I get the error message "subscript out of bounds" How can I solve it? Thanks in advance