From 50b61a3ee67ef5f699ad2fff412f8346fa8a1160 Mon Sep 17 00:00:00 2001
From: Jayce <jayce88@live.com.au>
Date: Thu, 17 Apr 2025 11:05:01 +0930
Subject: [PATCH] MDL-80053 core_grade: fixed exception message appearing

- Fixing the exceptions shows an incorrectly formatted table
- The filler cell is only used to take space on the left rows but when the right rows are empty, it is not needed.
---
 public/grade/lib.php               |  1 +
 public/grade/report/grader/lib.php | 26 +++++++++++++++++++-------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/public/grade/lib.php b/public/grade/lib.php
index 466a257b3c8..f0bebafb36c 100644
--- a/public/grade/lib.php
+++ b/public/grade/lib.php
@@ -2502,6 +2502,7 @@ class grade_tree extends grade_structure {
         $this->courseid   = $courseid;
         $this->levels     = array();
         $this->context    = context_course::instance($courseid);
+        $this->items      = [];
 
         if (!empty($COURSE->id) && $COURSE->id == $this->courseid) {
             $course = $COURSE;
diff --git a/public/grade/report/grader/lib.php b/public/grade/report/grader/lib.php
index 837fa93d40b..7c9b1ab007f 100644
--- a/public/grade/report/grader/lib.php
+++ b/public/grade/report/grader/lib.php
@@ -551,13 +551,19 @@ class grade_report_grader extends grade_report {
     public function get_max_students_per_page(): int {
         global $CFG;
 
+        $gradeitemcount = count($this->get_allgradeitems());
+
         if (isset($CFG->maxgradesperpage) && clean_param($CFG->maxgradesperpage, PARAM_INT) > 0) {
             $maxgradesperpage = $CFG->maxgradesperpage;
         } else {
             $maxgradesperpage = self::MAX_GRADES_PER_PAGE;
         }
 
-        return round($maxgradesperpage / count($this->get_allgradeitems()));
+		if ($gradeitemcount > 0) {
+			return round($maxgradesperpage / $gradeitemcount);
+		} else {
+			return $maxgradesperpage;
+		}
     }
 
     /**
@@ -662,7 +668,9 @@ class grade_report_grader extends grade_report {
         $fillercell->colspan = $colspan;
         $fillercell->rowspan = $levels;
         $row = new html_table_row(array($fillercell));
-        $rows[] = $row;
+        if ($levels >= 1) { // Do not display the filler cell if there are no levels as there will be nothing else in the row.
+            $rows[] = $row;
+        }
 
         for ($i = 1; $i < $levels; $i++) {
             $row = new html_table_row();
@@ -683,7 +691,6 @@ class grade_report_grader extends grade_report {
         $element = ['type' => 'userfield', 'name' => 'fullname'];
         $studentheader->text = $arrows['studentname'] .
             $this->gtree->get_cell_action_menu($element, 'gradeitem', $this->gpr, $this->baseurl);
-
         $headerrow->cells[] = $studentheader;
 
         foreach ($extrafields as $field) {
@@ -1299,10 +1306,15 @@ class grade_report_grader extends grade_report {
 
         // Extract rows from each side (left and right) and collate them into one row each
         foreach ($leftrows as $key => $row) {
-            $row->cells = array_merge($row->cells, $rightrows[$key]->cells);
-            $fulltable->data[] = $row;
-            unset($leftrows[$key]);
-            unset($rightrows[$key]);
+            if (isset($rightrows[$key])) {
+                $row->cells = array_merge($row->cells, $rightrows[$key]->cells);
+                $fulltable->data[] = $row;
+                unset($leftrows[$key]);
+                unset($rightrows[$key]);
+            } else { // Right row is not set - this is the case of the left side.
+                $fulltable->data[] = $row;
+                unset($leftrows[$key]);
+            }
         }
         $html .= html_writer::table($fulltable);
         return $OUTPUT->container($html, 'gradeparent');