Undefined Offset error in ExpressionEngine Parser.php line 52

Question

Using EE 3.1.4

Everything worked fine, until I changed the relationship selection to a new one. When I did that, it gave me the error. Now, even if I select the previously related field, I get the errors.

The message I get is :

Notice Undefined offset: 65

ee/legacy/libraries/relationship_parser/Parser.php, line 52 show details

Severity: E_NOTICE

---

Warning Cannot modify header information - headers already sent by (output started at /system/ee/legacy/core/Exceptions.php:112)

ee/EllisLab/ExpressionEngine/Boot/boot.common.php, line 459 show details

Severity: E_WARNING

Nothing changed in the template code or the entries except for the relationship selection.

---

EDIT

I have narrowed it down to a parsing issue somewhere in regards to a stash list. (See the following)

Everything was working until I changed the relationship entry to another entry. Now, even when I change back, I get the errors.

I am using the following embed:

{stash:embed:data:content_variables
    stash:channel="home_page"
    stash:segment_data="home"
    stash:limit="1"
    stash:dynamic="no"
    stash:status=""
    stash:order_by=""
    stash:paginate=""
    stash:url_title=""
}

This pulls in data from an embed template here:

{exp:switchee parse="inward" variable="{stash:segment_data}"}
    {case value="home"}
        {exp:channel:entries
            channel="{stash:channel}"
            dynamic="{stash:dynamic}"
            limit="{stash:limit}"
            status="{stash:status}"
            order_by="{stash:order_by}"
            sort="{stash:sort}"
            paginate="{stash:paginate}"
        }
            {exp:stash:sv_title}{title}{/exp:stash:sv_title}
            {exp:stash:sv_url_title}{url_title}{/exp:stash:sv_url_title}
            {exp:stash:sv_entry_id}{entry_id}{/exp:stash:sv_entry_id}
            {exp:stash:sv_entry_date}{entry_date format="%Y %m %d"}{/exp:stash:sv_entry_date}
            {exp:stash:sv_edit_date}{edit_date format="%Y %m %d"}{/exp:stash:sv_edit_date}
            {exp:stash:set_list name="slideshow_images" parse_tags="yes"}
                {slideshow}
                    {slideshow:slider_images}
                        {stash:sv_slideshow_image}{image:url:slider-optimized}{/stash:sv_slideshow_image}
                        {stash:sv_slideshow_title}{image:title}{/stash:sv_slideshow_title}
                    {/slideshow:slider_images}
                {/slideshow}
            {/exp:stash:set_list}

I stopped it there because the slider images is where I am getting the problem. If I comment out the section:

{exp:stash:set_list name="slideshow_images" parse_tags="yes"}
    {slideshow}
        {slideshow:slider_images}
            {stash:sv_slideshow_image}{image:url:slider-optimized}{/stash:sv_slideshow_image}
            {stash:sv_slideshow_title}{image:title}{/stash:sv_slideshow_title}
        {/slideshow:slider_images}
    {/slideshow}
{/exp:stash:set_list}

it displays fine. But if I leave that set_list statement in, I get the following:

Notice:

Undefined offset: 65 ee/legacy/libraries/relationship_parser/Parser.php, line 52 show details

Severity: E_NOTICE

---

Warning:

Cannot modify header information - headers already sent by (output started at /system/ee/legacy/core/Exceptions.php:112) ee/EllisLab/ExpressionEngine/Boot/boot.common.php, line 459 show details

Severity: E_WARNING

What am I doing wrong here?

---

EDIT

Upon further testing, it appears to be an issue with ExpressionEngine since the following renders the exact same issue. :(

{exp:channel:entries
    channel="home_page"
    dynamic="no"
    limit="1"
}

    {slideshow}
        {slideshow:slider_images}
            {image:url:slider-optimized}
            {image:title}
        {/slideshow:slider_images}
    {/slideshow}

{/exp:channel:entries} 

Answer 1

This happens when you delete a record with the help of a query eg. delete FROM exp_relationships where child_id = xxx.

Answer 2

This was eventually answered and I verified it here: https://support.ellislab.com/bugs/detail/21793

Essentially, if you delete/remove an entry that was related somewhere, you get this. It was not performed through query.