ShowTabByIndexAsync NullReference Exception

[curtic00]

Hi, has anyone seen this behaviour before? it's a bit random, mainly come up in playwright testing...

"Blazor.Bootstrap" Version="3.4.0"

net 8 server project

Note: some of the markup tags removed so that is shows up

@page "/Settings/WorkLogs"
@{

}

@using Simpson.Data.Interfaces;
@using Simpson.Data.Models;
using Microsoft.AspNetCore.Http

@Inject IJobData data
@Inject AuthenticationStateProvider AuthenticationStateProvider
@Inject ILogger logger;

PageTitle>Simpson Job Manager Settings : Work logs
AuthorizeView Roles="XYZ" Context="authContext">
Authorized>
h3 data-testid="dtWorkLogManagementCaption">WorkLog Management

    <Spinner Class="me-3" Type="SpinnerType.Dots" Color="SpinnerColor.Primary" id="idSpinner" Visible="@loading"  />
    <div>
        <Tabs @ref="tabs">
            <Tab Title="WorkLog Types Activities" Active="true" Name="WorkLogTypesTab" Id="IDWorkLogTypesTab">
                <Content>
                    <div class="container-fluid">
                        <Grid TItem="WorkLogTypeModel"
                        Class="table table-hover border-top table-striped"
                        Data="workLogTypes"
                        Responsive=true
                        HeaderRowCssClass="bg-primary text-white border-bottom-0"
                        GridContainerClass="mt-2">

                            <GridColumns>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Id">
                                    <span data-testid="dtWorkLogTypesID">@context.WLTID</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Work Type">
                                    <span data-testid="dtWorkLogTypesWorkType">@context.WorkType</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Rate Modifier">
                                    <span data-testid="dtWorkLogTypesRateModifier">@context.RateModifier</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Active">
                                    <span data-testid="dtWorkLogTypesActive">@context.Active</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Created By">
                                    <span data-testid="dtWorkLogTypesCreatedBy">@context.CreatedBy</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Created Date">
                                    <span data-testid="dtWorkLogTypesCreateDate">@context.CreateDate</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Edited by">
                                    <span data-testid="dtWorkLogTypesEditedBy">@context.EditedBy</span>
                                </GridColumn>
                                <GridColumn TItem="WorkLogTypeModel" HeaderText="Edited Date">
                                    <span data-testid="dtWorkLogTypesEditDate">@context.EditDate</span>
                                </GridColumn>
                            </GridColumns>
                        </Grid>
                    </div>
                </Content>
            </Tab>

            <Tab Title="Bank Holidays" Name="BankHolidaysTab" Id="IDBankHolidaysTab">
                <Content>
                    <Grid TItem="BankHoliday"
                    Class="table table-hover border-top table-striped"
                    Data="bankHolidays"
                    Responsive=true
                    HeaderRowCssClass="bg-primary text-white border-bottom-0" GridContainerClass="mt-2">

                        <GridColumns>
                            <GridColumn TItem="BankHoliday" HeaderText="Holiday Year">
                                <span data-testid="dtWorkLogBankHolidaysYear">@context.HolidayYear</span>
                            </GridColumn>
                            <GridColumn TItem="BankHoliday" HeaderText="Holiday Date">
                                <span data-testid="dtWorkLogBankHolidaysDate">@context.HolidayDate.ToString("dd-MMM-yyyy")</span>
                            </GridColumn>
                            <GridColumn TItem="BankHoliday" HeaderText="Holiday">
                                <span data-testid="dtWorkLogBankHolidaysDescription">@context.HolidayDescription</span>
                            </GridColumn>
                            <GridColumn TItem="BankHoliday" HeaderText="Create Date">
                                <span data-testid="dtWorkLogBankHolidaysCreateDate">@context.CreateDate.ToString("dd-MM-yyyy")</span>
                            </GridColumn>
                            <GridColumn TItem="BankHoliday" HeaderText="Created by">
                                <span data-testid="dtWorkLogBankHolidaysEditor">@context.Editor</span>
                            </GridColumn>

                        </GridColumns>
                    </Grid>
                </Content>
            </Tab>

            <Tab Title="WorkLog Time Slots" Name="WorkLogTimeSlotsTab" Id="IDWorkLogTimeSlotsTab">
                <Content>
                    <Grid TItem="TimeSlotModel"
                    Class="table table-hover border-top table-striped"
                    Data="timeSlots"
                    Responsive=true
                    HeaderRowCssClass="bg-primary text-white border-bottom-0" GridContainerClass="mt-2">

                        <GridColumns>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Id">
                                <span data-testid="dtWorkLogTimeSlotID">@context.WLSlotID</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Slot Time">
                                <span data-testid="dtWorkLogTimeSlotTime">@context.SlotTime</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Rate Modifier">
                                <span data-testid="dtWorkLogTimeSlotRateModifier">@context.RateModifier</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Created By">
                                <span data-testid="dtWorkLogTimeSlotCreatedBy">@context.CreatedBy</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Created Date">
                                <span data-testid="dtWorkLogTimeSlotCreateDate">@context.CreateDate</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Edited by">
                                <span data-testid="ddtWorkLogTimeSlotEditedBy">@context.EditedBy</span>
                            </GridColumn>
                            <GridColumn TItem="TimeSlotModel" HeaderText="Edited Date">
                                <span data-testid="dtWorkLogTimeSlotEditDate">@context.EditDate</span>
                            </GridColumn>
                        </GridColumns>
                    </Grid>
                </Content>
            </Tab>

        </Tabs>

    </div>

</Authorized>
<NotAuthorized>
    <Alert Color="AlertColor.Danger">
        <h4 class="alert-heading"><Icon Name="IconName.SignStopFill" class="me-2"></Icon>Access Denied!</h4>
        <p data-testid="dtSettingsWorklogsNotAuthorized">You're not authorized to manage settings in the job manager. Please contact the office for further information and assitance..</p>
        <hr>
    </Alert>
</NotAuthorized>

@code {
Tabs? tabs;

List<WorkLogTypeModel> workLogTypes = new List<WorkLogTypeModel>();
List<BankHoliday> bankHolidays = new List<BankHoliday>();
List<TimeSlotModel> timeSlots = new List<TimeSlotModel>();

Boolean loading = false;


protected override async Task OnInitializedAsync()