Make Leaflet map in Shiny interactive

[amal]

Hi! I want to make a map from a geojson file of eviction rates by county and when you hover over the county, it tells you the name and eviction rate for the county. However, I can't get it to work when I try to make it reactive. I am using data from the Princeton Eviction lab that I downloaded. It has a bunch of variables for different years. For instance, er-01 means the eviction rate in 2001. er-16 means the eviction rate in 2016. The data is from 2000 until 2016. Here is the reprex. Essentially, I want the fill of each county to be the eviction rate and update by year when the user selects a year. Any help is appreciated!
The following code returns this error: Error in as.vector(x, "list") :
cannot coerce type 'closure' to vector of type 'list'

library(shiny)
library(leaflet)
library(htmltools)
library(sf)

ui <- fluidPage(theme = shinytheme("flatly"),
                
                navbarPage("Rental Landscape of Ohio",
                           
                           # Adding a tab for my about page
                           tabPanel("Eviction Map",
                                    sidebarPanel(
                                      selectInput("mapvar",
                                                  label = "Choose",
      # the following are var names so sf$er.00 is eviction rate in 2000 and er. 01 is 2001
                                                  choices = c("2000" = "sf$`er.00`", "2001" = "sf$`er.01`",
                                                              "2002" = "sf$`er.02`", "2003" = "sf$`er.03`")
                                                  )
                                    ),
                                    mainPanel(
                                      leafletOutput("evicmap")))))


server <- function(input, output){
  sf <- read_sf(
    "https://raw.githubusercontent.com/amalabdi/milestone_8/master/counties.geojson") 


  pal_val <- reactive({
    as.character(input$mapvar)
  })
  pal<- reactive ({
    colorNumeric("viridis", pal_val(), domain = NULL)
  })
# creating labels for each county so when I hover over it, it tells me the eviction rate
  labels <- reactive({sprintf(
    "<strong>%s</strong><br/>%g percent eviction rate",
    sf$n, input$mapvar
  )}) %>% 
   lapply(htmltools::HTML)
  
  output$evicmap <- renderLeaflet({
    leaflet(sf) %>%
      addProviderTiles(providers$Stamen.Toner) %>%
      addPolygons(color = ~pal()(pal_val),
                  fillColor = ~pal()(pal_val),
                  highlight = highlightOptions(weight = 5,
                                               fillOpacity = 0.7,
                                               bringToFront = TRUE),
                  label = labels()
      ) %>% 
      addLegend(pal = pal(), values = pal_val())
  })
}

if it helps, here is the code that I am trying to update so it changes by year. It currently is using er.03 which is 2003 eviction rate:

library(shiny)
library(leaflet)
library(htmltools)
library(sf)
sf <- read_sf(
  "https://raw.githubusercontent.com/amalabdi/milestone_8/master/counties.geojson")
pal_val <- sf$er.03
pal <- colorNumeric("viridis", pal_val)
labels <- sprintf(
  "<strong>%s</strong><br/>%g percent eviction rate",
  sf$n, sf$er.03
) %>% 
  lapply(htmltools::HTML)

leaflet(sf) %>%
  addProviderTiles(providers$Stamen.Toner) %>%
  addPolygons(color = ~pal(pal_val),
              fillColor = ~pal(pal_val),
              highlight = highlightOptions(weight = 5,
                                           fillOpacity = 0.7,
                                           bringToFront = TRUE),
              label = labels
              ) %>% 
  addLegend(pal = pal, values = pal_val)