How to resolve Error in .checkTypos(e, names_x) . Error received while using gsub function in R

In my data, column names are written as following

D/T  Temp [degCelc]  Pres [hPa]  SRad [W/m**2]  Rain [mm]  ARad [W/m**2]  Moist [%]  K [%]  Temp1  Press1

I want to change the column names to

D/T  Temp  Pres  SRad  Rain  ARad  Moist  K  Temp1  Press1

correct_column_names <- function(dt_list){
  lapply(dt_list, FUN = function(x){
    colnames(x) <- gsub("[degCelc]", "", colnames(x))
    colnames(x) <- gsub("[hPa]", "", colnames(x))
    colnames(x) <- gsub("[W/m**2]", "", colnames(x))
    colnames(x) <- gsub("[mm]", "", colnames(x))
    colnames(x) <- gsub("[%]", "", colnames(x))
    
    return(x)
  })
}

This ran successfully.

Later as one step in the code, I selected columns to process by

sel_col <- c('D/T', 'Temp', 'Pres', 'SRad', 'Rain', 'ARad')

This gives me error:

Error in .checkTypos(e, names_x) :
Object 'Temp1' not found. Perhaps you intended Moist [%], K [%] or 2 more

This is what you want:

cols <- c("D/T", "Temp [degCelc]", "Pres [hPa]", "SRad [W/m**2]", "Rain [mm]", "ARad [W/m**2]", "Moist [%]", "K [%]", "Temp1", "Press1")

# using base R 
gsub(" \\[.*\\]", "", cols)

# or using tidyverse

library(tidyverse)
str_replace(cols, " \\[.*\\]", "")

The issue is that in gsub("[hPa]", "", colnames(x)), the square brackets haven't been escaped, so they need to be escaped (this is a good guide to regex in R). So it matches any of "h", "P, or "a"- not the square brackets, nor the space before them:

gsub("[degCelc]", "", "Temp [degCelc]") # [1] "Tmp []"