fix crash in sparklines (tx Adrian)
fix crash in sparklines (tx Adrian)

MjAbuz/watchdog,MjAbuz/watchdog,ferranti/watchdog,ferranti/watchdog,aaronsw/watchdog,MjAbuz/watchdog,ferranti/watchdog,MjAbuz/watchdog,ferranti/watchdog,aaronsw/watchdog,aaronsw/watchdog