fix .emplace logic, #1102

CHANGELOG.md

@@ -2,6 +2,7 @@
 ##### Unreleased
 - Added a workaround of the Bun ~ 0.1.1 [bug](https://github.com/Jarred-Sumner/bun/issues/399) that define some globals with incorrect property descriptors and that causes a crash of `core-js`
 - Added a fix of the FF103+ `structuredClone` bugs ([1774866](https://bugzilla.mozilla.org/show_bug.cgi?id=1774866) (fixed in FF104) and [1777321](https://bugzilla.mozilla.org/show_bug.cgi?id=1777321) (still not fixed)) that now can clone errors, but `.stack` of the clone is an empty string
+- Fixed `{ Map, WeakMap }.prototype.emplace` logic, [#1102](https://github.com/zloirock/core-js/issues/1102)
 - Fixed order of errors throwing on iterator helpers
 
 ##### [3.23.3 - 2022.06.26](https://github.com/zloirock/core-js/releases/tag/v3.23.3)

packages/core-js/internals/map-emplace.js

@@ -10,9 +10,15 @@ module.exports = function emplace(key, handler) {
   var get = aCallable(map.get);
   var has = aCallable(map.has);
   var set = aCallable(map.set);
-  var value = (call(has, map, key) && 'update' in handler)
-    ? handler.update(call(get, map, key), key, map)
-    : handler.insert(key, map);
-  call(set, map, key, value);
-  return value;
+  var value, inserted;
+  if (call(has, map, key)) {
+    value = call(get, map, key);
+    if ('update' in handler) {
+      value = handler.update(value, key, map);
+      call(set, map, key, value);
+    } return value;
+  }
+  inserted = handler.insert(key, map);
+  call(set, map, key, inserted);
+  return inserted;
 };