Fix: NullException in SNMP OID selection

Author: BornToBeRoot

Source/NETworkManager/ViewModels/DNSLookupSettingsViewModel.cs

@@ -334,6 +334,8 @@ public DNSLookupSettingsViewModel()
             return !info.UseWindowsDNSServer;
         };
 
+        SelectedDNSServer = DNSServers.Cast<DNSServerConnectionInfoProfile>().FirstOrDefault(x => !x.UseWindowsDNSServer);
+        
         LoadSettings();
 
         _isLoading = false;
@@ -349,7 +351,7 @@ private void LoadSettings()
         CustomDNSSuffix = SettingsManager.Current.DNSLookup_CustomDNSSuffix;
         Recursion = SettingsManager.Current.DNSLookup_Recursion;
         UseCache = SettingsManager.Current.DNSLookup_UseCache;
-        QueryClasses = Enum.GetValues(typeof(QueryClass)).Cast<QueryClass>().OrderBy(x => x.ToString()).ToList();
+        QueryClasses = [.. Enum.GetValues<QueryClass>().Cast<QueryClass>().OrderBy(x => x.ToString())];
         QueryClass = QueryClasses.First(x => x == SettingsManager.Current.DNSLookup_QueryClass);
         //ShowOnlyMostCommonQueryTypes = SettingsManager.Current.DNSLookup_ShowOnlyMostCommonQueryTypes;
         UseTCPOnly = SettingsManager.Current.DNSLookup_UseTCPOnly;

Source/NETworkManager/ViewModels/SNMPOIDProfilesViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.ComponentModel;
+using System.Linq;
 using System.Windows.Data;
 using System.Windows.Input;
 using NETworkManager.Models.Network;
@@ -37,6 +38,8 @@ public SNMPOIDProfilesViewModel(Action<SNMPOIDProfilesViewModel> okCommand,
             return info.Name.IndexOf(search, StringComparison.OrdinalIgnoreCase) > -1 ||
                    info.OID.IndexOf(search, StringComparison.OrdinalIgnoreCase) > -1;
         };
+                
+        SelectedOIDProfile = OIDProfiles.Cast<SNMPOIDProfileInfo>().FirstOrDefault();
     }
 
     public ICommand OKCommand { get; }
@@ -54,6 +57,8 @@ public string Search
 
             OIDProfiles.Refresh();
 
+            SelectedOIDProfile = OIDProfiles.Cast<SNMPOIDProfileInfo>().FirstOrDefault();
+
             OnPropertyChanged();
         }
     }

Source/NETworkManager/ViewModels/SNMPViewModel.cs

@@ -655,9 +655,12 @@ private async Task OpenOIDProfileSelection()
         {
             childWindow.IsOpen = false;
             ConfigurationManager.Current.IsChildWindowOpen = false;
+                        
+            if (instance.SelectedOIDProfile == null)
+                return;
 
             Mode = instance.SelectedOIDProfile.Mode;
-            Oid = instance.SelectedOIDProfile.OID;
+            Oid = instance.SelectedOIDProfile?.OID;
         }, async _ => {
             childWindow.IsOpen = false;
             ConfigurationManager.Current.IsChildWindowOpen = false;

Source/NETworkManager/Views/SNMPOIDProfilesChildWindow.xaml

@@ -43,10 +43,10 @@
                                 Binding="{Binding (network:SNMPOIDProfileInfo.Mode)}"
                                 SortMemberPath="Mode"
                                 Width="1*" />
-                </DataGrid.Columns>
+                </DataGrid.Columns>                
                 <DataGrid.InputBindings>
                     <KeyBinding Command="{Binding Path=OKCommand}" Key="Return" />
-                </DataGrid.InputBindings>
+                </DataGrid.InputBindings>                
                 <DataGrid.RowStyle>
                     <Style TargetType="{x:Type TypeName=DataGridRow}"
                    BasedOn="{StaticResource ResourceKey=MahApps.Styles.DataGridRow}">