Undefined index highlight_partial - Search API bug patch

The following error message appears when using the search bar: "Undefined index: highlight_partial in SearchApiHighlight->createExcerpt() (rule 363 of /var/www/html/web/sites/all/modules/contrib/search_api/includes/processor_highlight.inc)."

A patch has been created and applied to the dev branch but not to Search API 7.x-1.26.

Issue: Issue ticket
Patch: Patch URL