kded: Fix crash when low/high range and marker-levels lists are invalid

Mike Noerequested to merge
work/noee/kded-crash-517148 into master

It appears CUPS can send the level list and/or the range (low/high) list that have different counts than the level list or actually be empty. These lists should all have the same count.

So, don't use the level list count as the loop control, instead use the names list.

Also, found that low-level boundary can actually be 0, so check for that. That is not related to the crash, it just makes the checker ignore that level check.

Tested with corrupted list counts and values. See below for example of an invalid levels list

Attribute marker-colors \#00CFFF#F200FF#FFDA00,#000000
Attribute marker-levels 66,0,0,0,3,1,0,0
Attribute marker-low-levels 15,15
Attribute marker-high-levels 100,100
Attribute marker-names Color,Black
Attribute marker-types ink-cartridge,ink-cartridge
Attribute marker-change-time 1773163539

BUG: 517148 BUG: 517394 FIXED-IN: 6.6.4

Edited by Mike Noe

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