message: fix: update row parents list if all rows are deleted
diff: @@ -37,7 +37,7 @@ export class DiagramComponent implements OnChanges, OnDestroy {
  @Input() @HostBinding('class.flogo-diagram-is-readonly') isReadOnly = false;
  @Output() action = new EventEmitter<DiagramAction>();
  tileMatrix: TileMatrix;
  - rowParentsList: string[][] = [];
  + rowParentsList: string[][];
  trackRowBy: TrackByFunction<Tile[]>;
  @@ -67,16 +67,15 @@ export class DiagramComponent implements OnChanges, OnDestroy {
  private updateMatrix() {
  const tileMatrix = makeRenderableMatrix(this.flow, 10, this.isReadOnly);
  this.rowIndexService.updateRowIndexes(tileMatrix);
  - if (tileMatrix.length > 1) {
  + this.rowParentsList = [];
  + if (tileMatrix.length > 0) {
  const rowParentsList = this.updateRowParentsList(tileMatrix);
  // matrix is reversed to make sure html stack order always goes from bottom to top
  // i.e. top rows are rendered in front of bottom rows, this ensures branches don't display on top of the tiles above
  this.tileMatrix = tileMatrix.reverse();
  this.rowParentsList = rowParentsList.reverse();
  - } else if (tileMatrix.length === 0 && !this.isReadOnly) {
  + } else if (!this.isReadOnly) {
  this.tileMatrix = EMPTY_MATRIX;
  - } else {
  - this.tileMatrix = tileMatrix;
  }
  }
  