The Cannot read properties of null (reading 'forEach') exception is t…

…hrown on an attempt to run a survey fix #7341 (#7342)
surveyjs · Nov 14, 2023 · df52ca7 · df52ca7
1 parent e16688e
commit df52ca7
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diff --git a/src/question_matrixdropdownbase.ts b/src/question_matrixdropdownbase.ts
@@ -1831,6 +1831,7 @@ export class QuestionMatrixDropdownModelBase extends QuestionMatrixBaseModel<Mat
     this.collectNestedQuestonsInRows(this.visibleRows, questions, visibleOnly);
   }
   protected collectNestedQuestonsInRows(rows: Array<MatrixDropdownRowModelBase>, questions: Question[], visibleOnly: boolean): void {
+    if(!Array.isArray(rows)) return;
     rows.forEach(row => {
       row.questions.forEach(q => q.collectNestedQuestions(questions, visibleOnly));
     });

diff --git a/tests/question_matrixdropdownbasetests.ts b/tests/question_matrixdropdownbasetests.ts
@@ -943,4 +943,27 @@ QUnit.test("checkIfValueInRowDuplicated has only one duplicated error", function
   matrix.checkIfValueInRowDuplicated(row, q);
   assert.equal(q.errors.length, 1, "One error only");
   assert.equal(q.errors[0].getErrorType(), "keyduplicationerror", "Correct error is added");
+});
+QUnit.test("checkIfValueInRowDuplicated has only one duplicated error", function (assert) {
+  const survey = new SurveyModel({
+    "elements": [
+      {
+        "type": "matrixdynamic",
+        "name": "matrix",
+        "state": "collapsed",
+        "columns": [
+
+          {
+            "name": "col1",
+            "cellType": "dropdown",
+            "choices": ["a", "b"],
+            "showOtherItem": true,
+            "storeOthersAsComment": true
+          }
+        ]
+      }
+    ]
+  });
+  const matrix = <QuestionMatrixDropdownModelBase>survey.getQuestionByName("matrix");
+  assert.equal(matrix.columns.length, 1, "There is one column, it is loaded correctly");
 });