fix: nil pointer in PrefixSet Append

1 files changed, 6 insertions, 0 deletions

diff --git a/internal/pkg/table/policy.go b/internal/pkg/table/policy.go
index 44feebd6..6e97723c 100644
--- a/internal/pkg/table/policy.go
+++ b/internal/pkg/table/policy.go
@@ -370,6 +370,12 @@ func (lhs *PrefixSet) Append(arg DefinedSet) error {
 	if !ok {
 		return fmt.Errorf("type cast failed")
 	}
+
+	if rhs.tree.Len() == 0 {
+		// if try to append an empty set, then return directly
+		return nil
+	}
+
 	// if either is empty, family can be ignored.
 	if lhs.tree.Len() != 0 && rhs.tree.Len() != 0 {
 		_, w, _ := lhs.tree.Minimum()