message: hide link to previous block for open blocks
diff: </a>
  </div>
  </div>
  - <div class="uk-margin" *ngIf="transaction?.contents?.previous">
  + <div class="uk-margin" *ngIf="transaction?.contents?.previous && (blockType != 'open')">
  <label class="uk-form-label">Previous:</label>
  <div class="uk-form-controls uk-text-truncate">
  <a [routerLink]="'/transaction/' + transaction?.contents?.previous" class="uk-link-text" uk-tooltip title="View Block Details">{{ transaction?.contents?.previous }}</a>
  