Error when I run get_positions() about robinhood HOT 1 OPEN

custom_get_positions = function (RH, limit_output = TRUE){
    RobinHood::check_rh(RH)
    positions <- RobinHood::api_positions(RH)
    if (nrow(positions) == 0) {
      return(cat("You have no current positions"))
    }
    instrument_id <- positions$instrument
    instruments <- c()
    for (i in 1:length(instrument_id)) {
      instrument <- RobinHood::api_instruments(RH, instrument_url = instrument_id[i])
      x <- data.frame(simple_name = ifelse(is.null(instrument$simple_name), 
                                           instrument$name, instrument$simple_name), symbol = instrument$symbol)
      instruments <- rbind(instruments, x)
    }
    positions <- cbind(instruments, positions)
    symbols <- paste(as.character(positions$symbol), collapse = ",")
    symbols_url <- paste(RobinHood::api_endpoints(endpoint = "quotes"), 
                         symbols, sep = "")
    quotes <- RobinHood::api_quote(RH, symbols_url)
    quotes <- quotes[, c("last_trade_price", "symbol")]
    positions <- merge(positions[,!duplicated(colnames(positions))], quotes, by.x = 'symbol', by.y = 'symbol')
    positions <- positions[, !names(positions) %in% c("account", 
                                                      "url", "instrument")]
    positions$updated_at <- lubridate::ymd_hms(positions$updated_at)
    positions$created_at <- lubridate::ymd_hms(positions$created_at)
    positions$quantity <- as.numeric(positions$quantity)
    positions$average_buy_price <- as.numeric(positions$average_buy_price)
    positions$last_trade_price <- as.numeric(positions$last_trade_price)
    positions$shares_held_for_stock_grants <- as.numeric(positions$shares_held_for_stock_grants)
    positions$shares_held_for_options_events <- as.numeric(positions$shares_held_for_options_events)
    positions$shares_held_for_options_collateral <- as.numeric(positions$shares_held_for_options_collateral)
    positions$shares_held_for_buys <- as.numeric(positions$shares_held_for_buys)
    positions$shares_held_for_sells <- as.numeric(positions$shares_held_for_sells)
    positions$shares_pending_from_options_events <- as.numeric(positions$shares_pending_from_options_events)
    positions$pending_average_buy_price <- as.numeric(positions$pending_average_buy_price)
    positions$intraday_average_buy_price <- as.numeric(positions$intraday_average_buy_price)
    positions$intraday_quantity <- as.numeric(positions$intraday_quantity)
    positions$cost <- positions$average_buy_price * positions$quantity
    positions$current_value <- positions$last_trade_price * 
      positions$quantity
    if (limit_output == TRUE) {
      positions <- positions[, c("simple_name", "symbol", 
                                 "quantity", "average_buy_price", "last_trade_price", 
                                 "cost", "current_value", "updated_at")]
    }
    if (limit_output == FALSE) {
      positions <- positions[, c("symbol", "simple_name", 
                                 "quantity", "average_buy_price", "last_trade_price", 
                                 "cost", "current_value", "shares_held_for_stock_grants", 
                                 "shares_held_for_options_events", "shares_held_for_options_collateral", 
                                 "shares_held_for_buys", "shares_held_for_sells", 
                                 "shares_pending_from_options_events", "pending_average_buy_price", 
                                 "intraday_average_buy_price", "intraday_quantity", 
                                 "created_at", "updated_at")]
    }
    return(positions)
}

environment(custom_get_positions) <- asNamespace('RobinHood')
assignInNamespace("get_positions", custom_get_positions, ns = "RobinHood")