Adding states labels to plotly map created using plot_geo

Question

I'm working on an R shiny app and I have a dataframe with States and Population data that I'm trying to plot with plotly. This is my code:

# create a vector of state abbreviations
abbreviations <- c("AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA", "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD", "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ", "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC", "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY")

# create a vector of state populations
populations <- c(4903185, 731545, 7278717, 3017825, 39538223, 5758736, 3565287, 973764, 21477737, 10617423, 1415872, 1787065, 12671821, 6732219, 3155070, 2913314, 4467673, 4648794, 1344212, 6045680, 6892503, 9986857, 5639632, 2976149, 6137428, 1068778, 1934408, 3080156, 1359711, 8882190, 2096829, 19453561, 10488084, 762062, 11689100, 3956971, 4217737, 12801989, 1059361, 5148714, 884659, 6829174, 28995881, 3205958, 623989, 8535519, 7693612, 1792147, 5822434, 1793716, 578759)

# create the dataframe
us_states <- data.frame(state = abbreviations, population = populations)

aa_plotly__create_US_states_map <- function(df, states_col='',data_col='',
                                            plot_title='U.S. States map', colors_var = 'YlGn', colors_bar_title='', colors_bar_tickprefix = '', show_lakes=T,
                                            boundareies_line_width = 1.0, display_states_labels=F, states_labels_text_size=12,
                                            verbose=F, verbose_debug=F){
  # resources:
  #  https://plotly.com/r/builtin-colorscales/
  # https://plotly.com/r/choropleth-maps/    it shows also example to plot counties
  # https://search.r-project.org/CRAN/refmans/plotly/html/plot_geo.html   example of longitude and altitude
  
  if(colors_bar_title==''){
    colors_bar_title = data_col
  }
  
  df$hover <- paste0('State: ',df[,states_col], '<br>', data_col, df[, data_col])
  
  # light grey boundaries
  l <- list(color = toRGB("black"), width = boundareies_line_width)
  
  p <- plot_geo(df, locationmode = "USA-states") %>%
    add_trace(z = df[, data_col]
              , locations = df[,states_col]
              #, text = df[,states_col]
              , color = df[, data_col]
              , colors = colors_var # working values  "Purples", "RdBu"   https://plotly.com/r/builtin-colorscales/
              , showscale = T
              , text = df$hover
              , marker = list(line = l)
              ) %>% 
    colorbar(title = colors_bar_title
            , tickprefix = colors_bar_tickprefix # colors_bar_tickprefix can get values like  '$'
            ) %>%  
    layout(title = plot_title, 
           geo = list(scope = "usa" #if i omit this, i get the entire world!, another accepted value is  'europe'
                      #,projection = list(type = 'albers usa')
                      , showlakes = show_lakes
                      #,lakecolor = toRGB('white')
                      )
                 )
  
  if(display_states_labels){
        # https://stackoverflow.com/questions/68181278/adding-labels-to-plotly-map-created-using-plot-geo
        p <- p %>% add_trace(type = "scattergeo", locationmode = 'USA-states',
                             locations = df[,states_col], 
                             text = df[,states_col],
                             mode = "text",
                             textfont = list(color = rgb(0,0,0), 
                                             size = states_labels_text_size)
                             )
  }
  if(verbose) cat("\n\n========== aa_plotly__create_plot_with_subplots_that_all_have_same_xaxis ==================== \n\n")
  return(p)
}

aa_plotly__create_US_states_map(df, states_col='state',data_col='population',
                                  plot_title='U.S. States map', colors_var = 'YlGn', colors_bar_title='', colors_bar_tickprefix = '', show_lakes=T,boundareies_line_width = 1,display_states_labels=T, states_labels_text_size=12,
                                  verbose=F, verbose_debug=F)

Everything works well besides the labels part. I enhanced the function to add states labels using answer found here:Adding labels to plotly map created using plot_geo That part of code that add labels fails and does not add any label to the plot. What's wrong in the code? Thanks