This function checks which column has been set as the default wavenumber column. If no column has been set, it prints a message prompting the user to define one.
Value
If `show_val = TRUE`, returns the name of the wavenumber column (character). Otherwise, it only prints a message.
Examples
set_spec_wn("Wavenumber") # Set the wavenumber column
#> Successfully set 'Wavenumber' as the default wavenumber column.
check_wn_col() # Check which column is set
#> The current wavenumber column is: Wavenumber
check_wn_col(show_val = TRUE) # Check and return the column name
#> The current wavenumber column is: Wavenumber
#> [1] "Wavenumber"