   @spec handle_locked(current, Context.t) :: :locked
   defp handle_locked(current, ctx) do
     if current do
-      Process.cancel_timer(current.timer)
+      true = Process.cancel_timer(current.timer)
     end
     # Side effects.
     Farmbot.BotState.lock_bot(ctx)

        :ok = UART.write(state.nerves, str)
        {:noreply, %{state | current: current}}
      current ->
        next = %{state |
          current: current, status: current[:status] || :idle, timeouts: 0
        }

      }
      {:callback, writeme, current}
    else
      GenServer.reply(current.from, current.reply || "R02")
      nil
    end
  end
