message: fixed ko error "Cannot read property 'rowCounter' of null"
  fixed react setState usage for matrixdynamic
diff: @@ -11,6 +11,7 @@ export class SurveyQuestionMatrixDynamic extends SurveyQuestionElementBase {
  constructor(props: any) {
  super(props);
  this.setProperties(props);
  + this.state = this.getState()
  }
  protected get question(): QuestionMatrixDynamicModel { return this.questionBase as QuestionMatrixDynamicModel; }
  componentWillReceiveProps(nextProps: any) {
  @@ -18,14 +19,15 @@ export class SurveyQuestionMatrixDynamic extends SurveyQuestionElementBase {
  this.setProperties(nextProps);
  }
  private setProperties(nextProps: any) {
  - var self = this;
  this.setState({ rowCounter: 0 });
  - this.question.rowCountChangedCallback = function () {
  - self.state.rowCounter = self.state.rowCounter + 1;
  - self.setState(self.state);
  + this.question.rowCountChangedCallback = () => {
  + this.setState(this.getState(this.state));
  };
  this.handleOnRowAddClick = this.handleOnRowAddClick.bind(this);
  }
  + private getState(prevState = null) {
  + return {rowCounter: !prevState ? 0 : prevState.rowCounter + 1};
  + }
  handleOnRowAddClick(event) {
  this.question.addRow();
  }
  