Animating events on leaflet by year

[Godwin]

I am trying to use an animated slidebar to show conflict events per year since 1997. When It returns an Error: 'arg' must be NULL or a character vector.
I don't know what or where is the problem.
Here is the code

---

title: "Dashboard"
output:
flexdashboard::flex_dashboard:
orientation: columns
vertical_layout: fill
runtime: shiny

library(flexdashboard)
library(shiny)
library(DT)
library(dygraphs)
library(xts)
library(leaflet)
library(rgdal)

Column {data-width=200 .sidebar}

sliderInput("Year",
                          "DATE:",
                          min = as.Date("1997","%Y"),
                          max = as.Date("2020","%Y"),
                          value=as.Date("1997-01-01"),
                          step = 365,
                          timeFormat="%Y",
            animate = T)
c_events <- reactive({
    filter(data$lat, data$long, input$Year)
})

Column {data-width=650}

Map

data <- read.csv("Conflict_Kenya.csv")
sums <- read.csv("Conflict_Sums.csv")

data$long <- as.numeric(data$long)
data$lat <- as.numeric(data$lat)

data.SP <- SpatialPointsDataFrame(data[,c(5,6)], data[,-c(5,6)])
c_events <- reactive({
    filter(data$lat, data$long, input$Year)
})

renderLeaflet({
  c_events() %>% 
    leaflet() %>%
      addProviderTiles(providers$CartoDB.DarkMatter) %>%
      addCircleMarkers(radius = 1.3, color = "red", stroke = FALSE, fillOpacity = 0.6)    
})

Column {data-width=350}

Timetrend

sums <- read.csv("Conflict_Sums.csv")
dygraph(sums)