How to add buttons in Angular mat-table?

I’ve sucessfully used Angular mat-table to display data from database:

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<table mat-table [dataSource]="UserDataSourceFilters" class="mat-elevation-z1 mt-5">
            <ng-container [matColumnDef]="column" *ngFor="let column of displayedColumns">
                <th mat-header-cell *matHeaderCellDef>{{ getUserColumnDisplayName(column) }}</th>
                <td mat-cell *matCellDef="let emp">{{ emp[column] }}</td>
            </ng-container>
          
            <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
            <tr mat-row *matRowDef="let emprow; columns: displayedColumns" (click)="onRowExchangeClicked(emprow)"
                [ngClass]="{ 'clicked-row': true  }"></tr>
        </table>

        <mat-paginator [length]="100" [pageSize]="10" [pageSizeOptions]="[5, 10, 25, 100, 200]"
            aria-label="Select page">
        </mat-paginator>

Now I want to add another column, which contains buttons. So in component.ts, I add a new column called actions:

displayedColumns: string[] = ['firstName', 'lastName', 'email', ..., 'type','actions'];

and in my html i added this container:

<ng-container matColumnDef="actions">
                <mat-header-cell *matHeaderCellDef>actions</mat-header-cell>
                <mat-cell *matCellDef="let row">
                <button mat-button>Edit</button>
                </mat-cell>
            </ng-container>

But when i run the project, I got this error:

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