Call base() constructor for a bunch of objs

src/MayShow.Shared/Models/ReportFile.cs

@@ -12,7 +12,7 @@ class ReportFile : ChangeNotifier
     private string _notes;
     private string _filePath;
 
-    public ReportFile()
+    public ReportFile() : base()
     {
         _title = "";
         _receiptDateTime = DateTime.Now;

src/MayShow.Shared/ViewModels/BaseViewModel.cs

@@ -12,7 +12,7 @@ class BaseViewModel : ChangeNotifier
     IChangeViewModel _viewModelChanger;
     ITopLevelGrabber? _topLevelGrabber;
 
-    public BaseViewModel(IChangeViewModel viewModelChanger)
+    public BaseViewModel(IChangeViewModel viewModelChanger): base()
     {
         _viewModelChanger = viewModelChanger;
         _topLevelGrabber = null;

src/MayShow.Shared/ViewModels/MainViewModel.cs

@@ -9,7 +9,7 @@ class MainViewModel : ChangeNotifier, IChangeViewModel
     BaseViewModel _currentViewModel;
     Stack<BaseViewModel> _viewModels;
 
-    public MainViewModel(ITopLevelGrabber topLevelGrabber)
+    public MainViewModel(ITopLevelGrabber topLevelGrabber): base()
     {
         _viewModels = new Stack<BaseViewModel>();
         var initialViewModel = new StartNewChooseReportViewModel(this)

src/MayShow.Shared/ViewModels/SettingsViewModel.cs

@@ -29,7 +29,7 @@ class SettingsViewModel: ChangeNotifier
     private string _errorMessage;
     private ITopLevelGrabber? _topLevelGrabber;
 
-    public SettingsViewModel(Settings settingsToEdit, ITopLevelGrabber? topLevelGrabber)
+    public SettingsViewModel(Settings settingsToEdit, ITopLevelGrabber? topLevelGrabber): base()
     {
         _previousSettings = settingsToEdit;
         _settings = new Settings(settingsToEdit); // clone it

src/MayShow.Shared/ViewModels/WarningDeleteItemViewModel.cs

@@ -8,7 +8,7 @@ class WarningDeleteItemViewModel : ChangeNotifier
 {
     ReportFile _file;
 
-    public WarningDeleteItemViewModel(ReportFile file)
+    public WarningDeleteItemViewModel(ReportFile file): base()
     {
         _file = file;
     }