<div>
  <br/>
  <mat-form-field appearance="fill">
    <mat-label>Correct Fix</mat-label>
    <select matNativeControl (change)="changeFix($event)">
      <option value=""></option>
      <option *ngFor="let fix of randomFixes; index as i" [value]="i" 
      [selected]="selectedFix === i">Fix {{ i+1 }}</option>
    </select>
  </mat-form-field>
  <div *ngFor="let fix of randomFixes; index as i" id="code">
    <div  *ngIf="selectedFix === i">
      <td-ngx-text-diff [left]="snippet"
      [right]="fix?.fix"
      >
      </td-ngx-text-diff>
    </div>
  </div>
</div>
<div>
  <br/>
  <mat-form-field appearance="fill">
    <mat-label>Correct Fix</mat-label>
    <select matNativeControl (change)="changeFix($event)">
      <option *ngFor="let fix of randomFixes; index as i" [value]="i"
      [selected]="selectedFix === i">Fix {{ i+1 }}</option>
    </select>
  </mat-form-field>
  <div *ngFor="let fix of randomFixes; index as i" id="code">
    <div  *ngIf="selectedFix === i">
      <td-ngx-text-diff [left]="snippet"
      [right]="fix?.fix"
      >
      </td-ngx-text-diff>
    </div>
  </div>
</div>

Remove empty select option from code fixes dropdown
Remove empty select option from code fixes dropdown
