Fix null handling and update defaults/docs

README.md

@@ -27,7 +27,12 @@ Data
 Behavior notes (current)
 ------------------------
 - Suggested grade is calculated with 50/50 weighting (tests/competencies) as provided by the backend; “hard 0” for compilation errors removed.
-- Column renders percent when DTA data exists; nothing else is shown elsewhere.
+- Column renders percent when DTA data exists; nothing else is shown elsewhere. Missing DTA rows are handled gracefully (no output).
+
+Release package
+---------------
+- Top-level folder: `assignfeedback_dta` (ready to unzip into `mod/assign/feedback`).
+- ZIP excludes VCS and assets: `.git`, `.assets`.
 
 Packaging
 ---------

locallib.php

@@ -130,10 +130,8 @@ class assign_feedback_dta extends assign_feedback_plugin {
             null,  // No description text - help only via help button
             null, array(0, 1));
         $mform->addHelpButton('assignfeedback_dta_gradeautomatically', 'grade_automatically', self::COMPONENT_NAME);
-        // Set default value from saved config, or 1 if not set yet.
-        // Default to disabled (0) if not set.
-        $defaultvalue = $this->get_config('gradeautomatically', 0);
-        $mform->setDefault('assignfeedback_dta_gradeautomatically', $defaultvalue);
+        // Default to disabled for new assignments.
+        $mform->setDefault('assignfeedback_dta_gradeautomatically', 0);
         $mform->setType('assignfeedback_dta_gradeautomatically', PARAM_BOOL);
         
         // Hide the checkbox if this feedback plugin (Dockerized Test Agent) is not enabled.
@@ -643,6 +641,9 @@ class assign_feedback_dta extends assign_feedback_plugin {
             $submission = $this->assignment->get_user_submission($grade->userid, false, -1);
             if (!empty($submission) && $this->are_dta_tables_available()) {
                 $dtasubmission = $this->get_dta_submission($this->assignment->get_instance()->id, $submission->id);
+                if ($dtasubmission === false) {
+                    $dtasubmission = null; // normalize missing record to null
+                }
             }
         }