fix modal text display constructor initialization

Author: Cenngo

src/Discord.Net.Interactions/Extensions/IDiscordInteractionExtensions.cs

@@ -133,10 +133,11 @@ public static async Task<Modal> ToModalAsync<T>(this IDiscordInteraction interac
                         }
                         break;
                     case TextDisplayComponentInfo textDisplayComponent:
-                        {
-                            var content = modalInstance is not null ? textDisplayComponent.Getter(modalInstance).ToString() : (textDisplayComponent.DefaultValue as string) ?? textDisplayComponent.Content;
-                            var componentBuilder = new TextDisplayBuilder(content);
-                            builder.AddTextDisplay(componentBuilder);
+                    {
+                        var instanceValue = modalInstance is not null ? textDisplayComponent.Getter(modalInstance).ToString() : null;
+                        var content = instanceValue ?? (textDisplayComponent.DefaultValue as string) ?? textDisplayComponent.Content;
+                        var componentBuilder = new TextDisplayBuilder(content);
+                        builder.AddTextDisplay(componentBuilder);
                         }
                         break;
                     default:

src/Discord.Net.Interactions/Info/Components/TextDisplayComponentInfo.cs

@@ -14,6 +14,6 @@ public class TextDisplayComponentInfo : ModalComponentInfo
 
     internal TextDisplayComponentInfo(TextDisplayComponentBuilder builder, ModalInfo modal) : base(builder, modal)
     {
-        Content = Content;
+        Content = builder.Content;
     }
 }