question

That has nothing to do with the error.

the node behind the variable names thelist, thesum are involved in collecting of items. Because you can bring items from more than two input ports into a combiner the table thelist gets updated for each row for input port two, three, four and so on. In total the combiner only counts the items entering him after the container item has entered. This is thesum. The variable nodes behind the pointers are “componentlist“ and “targetcompentsum”. You update the values of those both variables. “Componentlist” is the table of components through the input ports two, three, four,...

And “targetcomponentsum” gets the value of all items you want to collect together at the end. You don’t need to calculate how many you need additionally to the already collected, You updates only the total values to get at the end of collecting.

But you must be absolutely correct that componentlist column sum matches with targetcomponentsum otherwise the processing never starts or there won’t never enter another container item the combiner again.

What is the reason behind changing the target quantity? Does it have to do with the size or type of item? If so, you might consider combining items based on a different metric, like size or weight.

For example, instead of starting with a quantity of 10 items and then changing to 6 later, you might consider starting with a target size of 100 cubic feet. Each item would then be allocated a portion of the 100 ft^3 available until another item cannot fit.

This is just an idea - it might not be what you're looking to do, but I thought I'd throw it out there just in case. Hope it helps.