message: Fix the bug: exception on setting defaultValue for boolean column type in Matrix Dynamic question:
diff: @@ -671,6 +671,7 @@ export class QuestionMatrixDropdownModelBase extends Question implements IMatrix
  if(this.isMatrixValueEmpty(oldValue)) oldValue = null;
  var newValue = this.createNewValue(this.value);
  var rowValue = this.getRowValueCore(row, newValue, true);
  + if(!rowValue) rowValue = {};
  for (var key in rowValue) delete rowValue[key];
  if (newRowValue) {
  newRowValue = JSON.parse(JSON.stringify(newRowValue));
  