When using the Essential theme and opening Single View, for either a student or task, in the Grade Report a coding error is experienced.

"Coding error detected, it must be fixed by a programmer: Trying to reference an unknown block region side-pre

Debug info:
Error code: codingerror
Stack trace:
line 895 of /lib/blocklib.php: coding_exception thrown
line 995 of /lib/blocklib.php: call to block_manager->check_region_is_known()
line 1008 of /lib/blocklib.php: call to block_manager->ensure_instances_exist()
line 297 of /lib/blocklib.php: call to block_manager->ensure_content_created()
line 1032 of /theme/essential/renderers/core_renderer.php: call to block_manager->get_content_for_region()
line 1014 of /theme/essential/renderers/core_renderer.php: call to theme_essential_core_renderer->essential_blocks_for_region()
line 56 of /theme/essential/layout/report.php: call to theme_essential_core_renderer->essential_blocks()
line 915 of /lib/outputrenderers.php: call to include()
line 845 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line 861 of /grade/lib.php: call to core_renderer->header()
line 120 of /grade/report/singleview/index.php: call to print_grade_page_head()"

This error does not occur when using the Clean Theme.