I'm having some issues with adding item groups server-side. The idea is that I am copying the lines from one transaction onto another. In the code block that checks if the item type is a Group, it keeps telling me to input a value for 'amount'. I've also tried explicitly setting an amount in that same block, but still the same error when I go to commit the item.

for (let i = 0; i < q.getLineCount('item'); i++)
                {
                    if (groupItem)
                    {
                        opp.selectLine({sublistId: 'item',line: i})
                        opp.setCurrentSublistValue('item', 'quantity', q.getSublistValue('item', 'quantity', i))
                        opp.setCurrentSublistValue('item', 'rate', q.getSublistValue('item', 'rate', i))
                        opp.setCurrentSublistValue('item', 'amount', q.getSublistValue('item', 'amount', i))
                        opp.setCurrentSublistValue('item', 'price', q.getSublistValue('item', 'price', i))
                        igTotal += opp.setCurrentSublistValue('item', 'amount', q.getSublistValue('item', 'amount', i))
                    }
                    if (q.getSublistValue('item', 'itemtype', i) == 'EndGroup')
                    {
                        opp.setCurrentSublistValue('item', 'amount', igTotal)
                        groupItem = false
                        continue
                    }
                    if (!groupItem && q.getSublistValue('item', 'itemtype', i) != 'EndGroup' && !groupItem)
                    {
                        opp.selectNewLine({sublistId: 'item'})
                        opp.setCurrentSublistValue('item', 'item', q.getSublistValue('item', 'item', i))
                        opp.setCurrentSublistValue('item', 'quantity', q.getSublistValue('item', 'quantity', i))
                        if (opp.getCurrentSublistValue('item', 'itemtype') == "Group")
                        {
                            groupItem = true
                            opp.setCurrentSublistValue('item', 'amount', 123)
                            opp.commitLine({sublistId: 'item'}) //SCRIPT FAILS HERE.
                            continue 
                        }
                        opp.setCurrentSublistValue('item', 'rate', q.getSublistValue('item', 'rate', i))
                        opp.setCurrentSublistValue('item', 'amount', q.getSublistValue('item', 'amount', i))
                        opp.commitLine({sublistId: 'item'})                   
                    }

                }

make your code actually commit every line, your code currently only commits it sometimes

@battk opp.setCurrentSublistValue('item', 'groupsetup', true) got me past that commit that it kept failing on. Things are a little weird still, and it doesn't like me inputting data around the price in the other transaction, but this will be something I explore over the next few days.