Use PageHeader throughout the system

WebApp/Components/Features/Teams/Edit.razor

@@ -1,21 +1,27 @@
 @page "/teams/edit"
 @attribute [Authorize]
 @using Microsoft.EntityFrameworkCore
+@using WebApp.Components.Shared.Components
 @inject AppDbContext Context
 @inject NavigationManager NavigationManager
 
-<PageTitle>Edit Team - TSA Chapter Organizer</PageTitle>
-
-<MudText Typo="Typo.h3">Edit</MudText>
-<MudText Typo="Typo.h4">Team @(Team.ToString())</MudText>
-
 @if (Team is null)
 {
     <p><em>Loading...</em></p>
+    return;
 }
-else
-{
-    <EditForm method="post" Model="Team" OnValidSubmit="UpdateTeam" FormName="edit" Enhance>
+
+<PageHeader Title="Edit Team"
+    Subtitle=@Team.ToString()
+    ShowBackButton="true"
+    BackButtonUrl="/teams">
+    <ActionButtons>
+        <MudButton OnClick="UpdateTeam" Variant="Variant.Filled" Color="Color.Primary">Save</MudButton>
+        <MudButton Href="/teams" Variant="Variant.Text">Cancel</MudButton>
+    </ActionButtons>
+</PageHeader>
+
+<EditForm method="post" Model="Team" OnValidSubmit="UpdateTeam" FormName="edit" Enhance>
         <AntiforgeryToken />
         <DataAnnotationsValidator/>
         <MudGrid>
@@ -33,10 +39,7 @@ else
                 </MudPaper>
             </MudItem>
         </MudGrid>
-        <MudButton StartIcon="@Icons.Material.Filled.ArrowBack" Href="teams">Back</MudButton>
-        <MudButton StartIcon="@Icons.Material.Filled.Save" OnClick="UpdateTeam">Save</MudButton>
-    </EditForm>
-}
+</EditForm>
 
 @code {
     [SupplyParameterFromQuery]
@@ -45,7 +48,7 @@ else
     [SupplyParameterFromForm]
     private Team? Team { get; set; }
 
-    private IEnumerable<Student> _selectedStudents = [];
+    private IEnumerable<Student>? _selectedStudents = [];
     private List<Student> _students = [];
 
     protected override async Task OnInitializedAsync()
@@ -55,7 +58,7 @@ else
             .Include(e => e.Students)
             .FirstOrDefaultAsync(m => m.Id == Id);
         _students = await Context.Students.ToListAsync();
-        _selectedStudents = Team.Students.ToList();
+        _selectedStudents = Team?.Students.ToList();
 
         if (Team is null)
         {
@@ -68,6 +71,10 @@ else
                 Team.Captain ??= Team.Students[0];
                 Team.Identifier ??= Team.Captain.FirstName;
                 break;
+            case EventFormat.Team:
+                break;
+            default:
+                throw new ArgumentOutOfRangeException();
         }
     }
 
@@ -76,14 +83,15 @@ else
     private async Task UpdateTeam()
     {
         //Context.Attach(Team!).Entity = EntityState.Modified;
-        Team.Students.Clear();
-        foreach (var s in _selectedStudents)
-        {
-            Team.Students.Add(s);
-        }
+        Team?.Students.Clear();
+        if (_selectedStudents != null)
+            foreach (var s in _selectedStudents)
+            {
+                Team?.Students.Add(s);
+            }
 
         // Update identifier for individual events
-        if (Team.Event.EventFormat == EventFormat.Individual && Team.Students.Count == 1)
+        if (Team is { Event.EventFormat: EventFormat.Individual, Students.Count: 1 })
         {
             Team.Captain ??= Team.Students[0];
             Team.Identifier = Team.Captain.FirstName;