问如何在没有标题行的情况下渲染Angular 9 mat表？

EN

<table mat-table *ngIf="isMobile" #mobile_table [dataSource]="dataSource">
  <ng-container matColumnDef="item">
    <td mat-cell *matCellDef="let item_stat">
      <div class="smallHeading">
        {{ item_stat.max_date }} m
      </div>
      <div class="mainRow divider">
        <a href="{{ item_stat.mobile_path }}">{{ item_stat.title }}</a> ·
        {{ getScore(item_stat) }}
      </div>
    </td>
  </ng-container>

  <tr mat-header-row *matHeaderRowDef="mobileDisplayedColumns"></tr>
  <tr mat-row *matRowDef="let row; columns: mobileDisplayedColumns;" [ngClass]="getRowClass(row)"></tr>
</table>

ERROR TypeError: Cannot read property 'template' of undefined
    at MatHeaderRowDef.extractCellTemplate (table.js:567)
    at table.js:2522
    at Function.from (<anonymous>)
    at MatTable._getCellTemplates (table.js:2512)
    at MatTable._renderRow (table.js:2467)
    at table.js:2326
    at Array.forEach (<anonymous>)
    at MatTable._forceRenderHeaderRows (table.js:2321)
    at MatTable.ngAfterContentChecked (table.js:1800)
    at callHook (core.js:4730)

<th mat-header-cell *matHeaderCellDef></th>