diff --git a/backend/internal/adapter/llm/anyllm.go b/backend/internal/adapter/llm/anyllm.go
index 5668427..ece6a4d 100644
--- a/backend/internal/adapter/llm/anyllm.go
+++ b/backend/internal/adapter/llm/anyllm.go
@@ -168,13 +168,15 @@ func (e *AnyLLMEngine) Stream(
 					Extra: extra,
 				})
 
-				params.OnChunk(&domain.Chunk{
-					Done:      false,
-					ToolName:  tc.Function.Name,
-					Role:      anyllm.RoleAssistant,
-					Content:   tc.Function.Arguments,
-					Reasoning: false,
-				})
+				if params.OnChunk != nil {
+					params.OnChunk(&domain.Chunk{
+						Done:      false,
+						ToolName:  tc.Function.Name,
+						Role:      anyllm.RoleAssistant,
+						Content:   tc.Function.Arguments,
+						Reasoning: false,
+					})
+				}
 
 			}
 
@@ -182,11 +184,13 @@ func (e *AnyLLMEngine) Stream(
 	}
 
 	if !toolCalling {
-		params.OnChunk(&domain.Chunk{
-			Done:    true,
-			Role:    anyllm.RoleAssistant,
-			Content: "",
-		})
+		if params.OnChunk != nil {
+			params.OnChunk(&domain.Chunk{
+				Done:    true,
+				Role:    anyllm.RoleAssistant,
+				Content: "",
+			})
+		}
 	}
 
 	if err := <-errChan; err != nil {