Shiny page with global variables crashes - r

Question

I have some large shapefiles that I want to run some intersect analysis on using user input on a leaflet map. My shiny page displays a map that a user can draw a polygon on and I want to see if that polygon intersects either of the two shapefiles. I built a working version of this where the server reads in the shapefiles each time a user connects to the server, but obviously that isn't a great user experience. So I have been trying to move the shapefile reading to global variables that the server loads once, and the user just has to run the intersect on. I'll skip posting my 3 lines of UI for now but this app works locally, it's only when I run it on a dedicated Shiny server that is crashes after the user "closes" the polygon. I have a feeling it's an issue with the global variable declarations, but there is no log file generated so I'm having a really hard time debugging it.
App.R
library(shiny)
source("/ui.R")
source("/server.R")
shpfile1 <- st_read("path_to_shpfile1")
shpfile2 <- st_read("path_to_shpfile2")
ui <- ui()
server <- server()
shinyApp(ui = ui, server = server)
Server.R
# a number of libraries
server <- function(input, output, session) {
output$s1 <- renderText({"Define project area..."})
output$s2 <- renderText({"Define project area..."})
print("Reading New Jersey boundary...")
mapStates = map("state", "New Jersey", fill = FALSE, plot = FALSE)
output$map <- renderLeaflet({
leaflet(data = mapStates) %>% addTiles() %>% addPolygons(fillColor = topo.colors(10, alpha=0.8), stroke=FALSE) %>%
addDrawToolbar(targetGroup = "projectArea",
rectangleOptions = F,
polylineOptions = F,
markerOptions = F,
circleMarkerOptions = F,
editOptions = editToolbarOptions(edit = FALSE, remove = TRUE, selectedPathOptions = selectedPathOptions()),
circleOptions = F)
})
observeEvent(input$drawPoints, {
proxy %>% clearShapes()
for (i in seq_along(data)) {
proxy %>% addPolygons(
data[[i]][,"lon"],
data[[i]][,"lat"],
layerId=i,
opacity=0.4,
color = c('red','green')[i]
)
Sys.sleep(2) # - this is to see first (red) polygon
}
})
observeEvent(input$map_draw_new_feature, {
withProgress(message = "Please wait...", value = 0, {
# capture project area and convert to usable format for intersecting
feat <- input$map_draw_new_feature
coords <- unlist(feat$geometry$coordinates)
coords <- matrix(coords, ncol=2, byrow=TRUE)
poly <- st_sf(st_sfc(st_polygon(list(coords))), crs = "+proj=longlat +datum=WGS84")
# intersect project area with constraint layers
incProgress(1/3, detail = "Analyzing shapefile1...")
i_shp1 <- st_intersects(poly, shpfile1)
c_shp1 <- sapply(i_shp1, length)
incProgress(2/3, detail = "Analyzing shapefile2...")
i_shp2 <- st_intersects(poly, shpfile2)
c_shp2 <- sapply(i_shp2, length)
if(c_streams > 0) {
output$s1 <- renderText({"does intersect shapefile 1"})
} else {
output$s1 <- renderText({"does not intersect shapefile 1"})
}
if(c_wetlands > 0) {
output$s2 <- renderText({"does intersect shapefile 2"})
} else {
output$s2 <- renderText({"does not intersect shapefile 2"})
}
})
})
}