Checkout page hangs

[angelo983]

Wrong evaluating check of position param (Position at which item should be inserted.)
let hang Checkout Page

Preconditions

1. Centos 6.7 Final
2. Plesk 12.5 (Apache 2.2.15)
3. Magento 2.1.7
4. PHP 5.6
5. Existing set of configurable products and linked simple products

Steps to reproduce

1. Put in cart at least one simple product from a configurable product page
2. Go to checkout page

Expected result

1. Checkout page displays steps to complete payment.

Actual result

1. After waiting a bit, the body of the page rests blank
2. in console appears a javascript error: element position is null

Fixed Issues (if relevant)

lib/web/mage/utils/arrays.js
Line 105
from
if (typeof position === 'undefined') {
to
if (typeof position === 'undefined' || position == null) {

Manual testing scenarios

May happens while buying simple products of configurable products

[smoskaluk]

@angelo983 We cannot reproduce this issue as described. Please provide the detailed steps we must follow to reproduce this issue. In addition, identify the OS and web server you are running, the versions of MySQL, and any other information needed to reproduce your issue.

[angelo983]

I found a workaround for me by seeing this evidence in lib/web/mage/utils/arrays.js
Line 105 to 129

        if (typeof position === 'undefined') { // line 105 - fixed  issue above
            position = -1;
        } else if (typeof position === 'string') {
            position = isNaN(+position) ? position : +position;
        }

        newIndex = position;

        if (~currentIndex) {
            target = container.splice(currentIndex, 1)[0];

            if (typeof item === 'string') {
                item = target;
            }
        }

        if (typeof position !== 'number') {
            target = position.after || position.before || position; // line 122

            newIndex = getIndex(target, container);

            if (~newIndex && (position.after || newIndex >= currentIndex)) {
                newIndex++;
            }
        }

Browser console gave me error in line 122 because position value is NULL and this value is not managed in the script

[smoskaluk]

@angelo983 May you please give more detailed steps for reproducing this issue?

[angelo983]

No need to reproduce, there is a evidence of faulty variable check as I stated in previous post