How do I solve the following error?Input must be a character vector of any length or a list of character vectors, each of which has a length of 1.

I am working on a R project. The data set I used is available at the following link https://www.kaggle.com/ranjitha1/hotel-reviews-city-chennai/data

The code I have used is.

df1 = read.csv("chennai.csv", header = TRUE)
library(tidytext)
tidy_books <- df1 %>% unnest_tokens(word,Review_Text)

Here Review_Text is the text column. Yet, I get the following error.

Error in check_input(x) : 
Input must be a character vector of any length or a list of character
vectors, each of which has a length of 1.