Cannot get chr to convert to num

[CarolineBay]

I am new to using R and github so I apologize if this is incorrect formatting and/or bad github etiquette. I really want to learn how to use this package because it seems so helpful!

I am trying to convert a column (bmi) of my dataframe (nonbradypts) from chr to num

library("tidyverse") 
library("hablar")
nonbradypts %>%
  convert(num(bmi))

I get the error:

However, per my knowledge, bmi already does exist!

Doing nonbradypts$bmi = as.numeric(nonbradypts$bmi) is successful, however.

Thank you in advance, I'm sure I'm doing some beginner mistake...!