fix test

Author: qmuntal

go/internal/e2e/session_test.go

@@ -68,6 +68,10 @@ func TestSession(t *testing.T) {
 			t.Fatalf("Failed to send message: %v", err)
 		}
 
+		if assistantMessage == nil {
+			t.Fatal("Expected assistant message, got nil")
+		}
+
 		if assistantMessage.Data.Content == nil || !strings.Contains(*assistantMessage.Data.Content, "2") {
 			t.Errorf("Expected assistant message to contain '2', got %v", assistantMessage.Data.Content)
 		}
@@ -77,6 +81,10 @@ func TestSession(t *testing.T) {
 			t.Fatalf("Failed to send second message: %v", err)
 		}
 
+		if secondMessage == nil {
+			t.Fatal("Expected second assistant message, got nil")
+		}
+
 		if secondMessage.Data.Content == nil || !strings.Contains(*secondMessage.Data.Content, "4") {
 			t.Errorf("Expected second message to contain '4', got %v", secondMessage.Data.Content)
 		}