Fix silently discarded save failures in Language/DictionaryItem/Webhook serializers (#1040)

SaveItemAsync discarded the Attempt<T, Status> returned by ILanguageService,
IDictionaryItemService, and IWebhookService, so a failed create/update (e.g.
an ISO code rejected by Umbraco's IsoCodeValidator) was silently dropped
while the import still reported success. Now throws when the attempt fails,
so the failure surfaces in the import results and log instead of vanishing.

Fixes #1038

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: KevinJump

uSync.Core/Serialization/Serializers/DictionaryItemSerializer.cs

@@ -228,10 +228,18 @@ private async Task<int> GetLevelAsync(IDictionaryItem item, int level = 0)
     }
 
     public override async Task SaveItemAsync(IDictionaryItem item)
-        => _ = item.HasIdentity
+    {
+        var attempt = item.HasIdentity
             ? await _dictionaryItemService.UpdateAsync(item, Constants.Security.SuperUserKey)
             : await _dictionaryItemService.CreateAsync(item, Constants.Security.SuperUserKey);
 
+        if (attempt.Success is false)
+        {
+            throw new InvalidOperationException(
+                $"Could not save dictionary item {item.ItemKey}: {attempt.Status}");
+        }
+    }
+
     public override Task DeleteItemAsync(IDictionaryItem item)
         => _dictionaryItemService.DeleteAsync(item.Key, Constants.Security.SuperUserKey);
 

uSync.Core/Serialization/Serializers/LanguageSerializer.cs

@@ -152,10 +152,18 @@ public override bool IsValid(XElement node)
         => Task.FromResult(default(ILanguage));
 
     public override async Task SaveItemAsync(ILanguage item)
-        => _ = item.HasIdentity
+    {
+        var attempt = item.HasIdentity
             ? await _languageService.UpdateAsync(item, Constants.Security.SuperUserKey)
             : await _languageService.CreateAsync(item, Constants.Security.SuperUserKey);
 
+        if (attempt.Success is false)
+        {
+            throw new InvalidOperationException(
+                $"Could not save language {item.IsoCode}: {attempt.Status}");
+        }
+    }
+
     public override Task DeleteItemAsync(ILanguage item)
         => _languageService.DeleteAsync(item.IsoCode, Constants.Security.SuperUserKey);
 

uSync.Core/Serialization/Serializers/WebhookSerializer.cs

@@ -50,7 +50,17 @@ public override string ItemAlias(IWebhook item)
     /// <inheritdoc/>
     /// 
     public override async Task SaveItemAsync(IWebhook item)
-        => _ = item.HasIdentity ? await _webhookService.UpdateAsync(item) : await _webhookService.CreateAsync(item);
+    {
+        var attempt = item.HasIdentity
+            ? await _webhookService.UpdateAsync(item)
+            : await _webhookService.CreateAsync(item);
+
+        if (attempt.Success is false)
+        {
+            throw new InvalidOperationException(
+                $"Could not save webhook {item.Key}: {attempt.Status}");
+        }
+    }
 
     /// <inheritdoc/>
     protected override async Task<SyncAttempt<IWebhook>> DeserializeCoreAsync(XElement node, SyncSerializerOptions options)