deleting all matching items

There are four rectangles in the document. All of them have no fill AND no stroke. When I try to delete them all based on this condition, I get that only two of them are deleted. I expected all of them to be deleted. What is the problem?

var doc = app.activeDocument;
processItems(doc.pageItems);

function hasNoFillAndStroke(item) {
    return !item.filled && !item.stroked;
}

function processItems(items) {
    for (var i = 0; i < items.length; i++) {
        var item = items[i];

        if (hasNoFillAndStroke(item)) {
            alert(item.typename);
            item.remove();
        }
    }
}