What causes this "You have attempted an invalid sublist or line item operation. You are either trying to access a field on a non-existent line or you are trying to add or remove lines from a static sublist."

AI generated answer (using internal Slack threads):

The error "You have attempted an invalid sublist or line item operation. You are either trying to access a field on a non-existent line or you are trying to add or remove lines from a static sublist." typically occurs when you are trying to manipulate a sublist or line item in a way that is not allowed by NetSuite. From the conversations, there are a few common scenarios where this error might occur: 1. Order of setting columns: When adding a new line item, the order in which you set the fields matters. For example, you might get this error if you try to set the price of a line item before setting the item itself. Here's a corrected version of the code:

javascript
var newRecord = nlapiGetNewRecord();
newRecord.selectNewLineItem('item');
// Set the item before setting the price
newRecord.setCurrentLineItemValue('item', 'item', 'itemId');
newRecord.setCurrentLineItemValue('item', 'price', '1');
newRecord.commitLineItem('item');

2. Removing line items: When removing line items, make sure the line item exists before trying to remove it. Also, log your variables before the remove line item API to ensure they are correct. 3. Deleting sublist lines: When deleting sublist lines, the order in which you delete them matters. If you delete from the top down, you might mess up your index and get this error. Instead, delete from the bottom up. Here's an example:

javascript
for (var i = REC_LINES; i > 0; i--) {
    // Delete line i
}

Remember to always ensure that the line or sublist you are trying to manipulate exists and is not a static sublist, which cannot be modified. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******