Resolving warnings and treating warnings as errors in WinUI project. (#824)

Wino.Mail.WinUI/Services/ConfigurationService.cs

@@ -9,10 +9,10 @@ namespace Wino.Mail.WinUI.Services;
 
 public class ConfigurationService : IConfigurationService
 {
-    public T Get<T>(string key, T defaultValue = default)
+    public T Get<T>(string key, T defaultValue = default!)
         => GetInternal(key, ApplicationData.Current.LocalSettings.Values, defaultValue);
 
-    public T GetRoaming<T>(string key, T defaultValue = default)
+    public T GetRoaming<T>(string key, T defaultValue = default!)
         => GetInternal(key, ApplicationData.Current.RoamingSettings.Values, defaultValue);
 
     public void Set(string key, object value)
@@ -21,11 +21,13 @@ public class ConfigurationService : IConfigurationService
     public void SetRoaming(string key, object value)
         => SetInternal(key, value, ApplicationData.Current.RoamingSettings.Values);
 
-    private static T GetInternal<T>(string key, IPropertySet collection, T defaultValue = default)
+    private static T GetInternal<T>(string key, IPropertySet collection, T defaultValue = default!)
     {
-        if (collection.TryGetValue(key, out object value))
+        if (collection.TryGetValue(key, out object? value))
         {
             var stringValue = value?.ToString();
+            if (string.IsNullOrWhiteSpace(stringValue))
+                return defaultValue;
 
             if (typeof(T).IsEnum)
                 return (T)Enum.Parse(typeof(T), stringValue);
@@ -40,7 +42,8 @@ public class ConfigurationService : IConfigurationService
                 return (T)(object)TimeSpan.Parse(stringValue);
             }
 
-            return (T)Convert.ChangeType(stringValue, typeof(T));
+            var converted = Convert.ChangeType(stringValue, typeof(T));
+            return converted is T typed ? typed : defaultValue;
         }
 
         return defaultValue;