[CHANGE] Updated settings and added warning messages

Manager.App/Models/Settings/DownloadSettings.cs

@@ -5,6 +5,6 @@ namespace Manager.App.Models.Settings;
 public class DownloadSettings
 {
     [ConfigurationKeyName("MaxConcurrentDownloads")]
-    [Range(-1, 20)]
-    public int MaxConcurrentDownloads { get; set; }
+    [Range(-1, 20, ErrorMessage = "Max concurrent downloads must be between 0 and 20. (0 for unlimited concurrent downloads)")]
+    public int MaxConcurrentDownloads { get; set; } = 5;
 }

Manager.App/Models/Settings/LibrarySettings.cs

@@ -5,6 +5,10 @@ namespace Manager.App.Models.Settings;
 public class LibrarySettings
 {
     [ConfigurationKeyName("Path")]
-    [Required]
+    [Required(AllowEmptyStrings = false, ErrorMessage = "Library path is required!")]
     public required string Path { get; set; }
+
+    [ConfigurationKeyName("DefaultUserAgent")]
+    [Required(AllowEmptyStrings = false, ErrorMessage = "An default user agent is required.")]
+    public required string DefaultUserAgent { get; set; }
 }