re-set city/township selectinput box when county is cleared

[ashleyasmus]

maybe I need to turn off "ignoreNULL" in this part of mod_filters_oneway.R?

    observeEvent(input$oneway_input_counties,
                 {
                   if (!is.null(input$oneway_input_counties))
                   {
                     filtered_cities <- tbi_tables$hh %>%
                       dplyr::filter(hh_county %in% input$oneway_input_counties) %>%
                       dplyr::select(hh_city) %>%
                       unique() %>%
                       na.omit()

                     updateSelectInput(
                       session = session,
                       inputId = "oneway_input_cities",
                       label = "Household City/Township",
                       choices = filtered_cities$hh_city,
                       selected = NULL
                     )
                   } else {
                     selectInput(
                       session = session,
                       inputId = ns("oneway_input_cities"),
                       "Household City/Township",
                       choices = unique(na.omit(tbi_tables$hh$hh_city)),
                       selected = NULL)
                   }},
                 ignoreInit = TRUE
    )