install: fix checking for optional dep

See https://npm.community/t/2569
larsgw · Oct 7, 2018 · c81df49 · c81df49
1 parent 03840dc
commit c81df49
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/lib/install/is-only-optional.js b/lib/install/is-only-optional.js
@@ -10,6 +10,7 @@ function isOptional (node, seen) {
   if (seen.has(node) || node.requiredBy.length === 0) {
     return false
   }
+  seen = new Set(seen)
   seen.add(node)
   const swOptional = node.fromShrinkwrap && node.package._optional
   return node.requiredBy.every(function (req) {