minor change

Author: Jicheng Lu

src/Plugins/BotSharp.Plugin.Qdrant/QdrantDb.cs

@@ -230,13 +230,13 @@ public async Task<bool> Upsert(string collectionName, Guid id, float[] vector, s
         {
             foreach (var item in payload)
             {
-                if (item.Value == null)
+                if (item.Value == null || item.Key.IsEqualTo(KnowledgePayloadName.Text))
                 {
                     continue;
                 }
 
                 var value = item.Value.DataValue?.ConvertToString();
-                if (string.IsNullOrEmpty(value) || item.Key.IsEqualTo(KnowledgePayloadName.Text))
+                if (string.IsNullOrEmpty(value))
                 {
                     continue;
                 }