From 2d7bbf60cc53d0da68826459971e49088b8c849b Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 12 Sep 2023 15:34:09 +0530
Subject: [PATCH] Fix #6615

---
 tools/utils/set.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/utils/set.go b/tools/utils/set.go
index 70f9f8267..9965d0880 100644
--- a/tools/utils/set.go
+++ b/tools/utils/set.go
@@ -60,6 +60,9 @@ func (self *Set[T]) AsSlice() []T {
 }
 
 func (self *Set[T]) Intersect(other *Set[T]) (ans *Set[T]) {
+	if other == nil {
+		return NewSet[T]()
+	}
 	if self.Len() < other.Len() {
 		ans = NewSet[T](self.Len())
 		for x := range self.items {