message: [dashboard] Fix JS error when position_json data is empty
diff: @@ -34,10 +34,12 @@ export function getInitialState(bootstrapData) {
  dashboard.posDict = {};
  dashboard.layout = [];
  - if (dashboard.position_json) {
  + if (Array.isArray(dashboard.position_json)) {
  dashboard.position_json.forEach((position) => {
  dashboard.posDict[position.slice_id] = position;
  });
  + } else {
  + dashboard.position_json = [];
  }
  const lastRowId = Math.max.apply(null,
  dashboard.position_json.map(pos => (pos.row + pos.size_y)));
  