From 63e70fd3f1eae634f7160d68a3070369a90249d7 Mon Sep 17 00:00:00 2001
From: jdecroock <decroockjovi@gmail.com>
Date: Thu, 18 May 2023 14:23:02 +0200
Subject: [PATCH] simplify more checks

---
 src/diff/children.js | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/diff/children.js b/src/diff/children.js
index 5bedfe0691..47cbd75b1a 100644
--- a/src/diff/children.js
+++ b/src/diff/children.js
@@ -122,15 +122,11 @@ export function diffChildren(
 		if (matchingIndex === -1) {
 			oldVNode = EMPTY_OBJ;
 		} else {
-			oldVNode = oldChildren[matchingIndex];
+			oldVNode = oldChildren[matchingIndex] || EMPTY_OBJ;
 			oldChildren[matchingIndex] = undefined;
 			remainingOldChildren--;
 		}
 
-		oldVNode = oldVNode || EMPTY_OBJ;
-		let isMounting =
-			isHydrating || oldVNode === EMPTY_OBJ || oldVNode._original === null;
-
 		// Morph the old element into the new one, but don't append it to the dom yet
 		diff(
 			parentDom,
@@ -157,12 +153,13 @@ export function diffChildren(
 				firstChildDom = newDom;
 			}
 
+			let isMounting = oldVNode === EMPTY_OBJ || oldVNode._original === null;
 			let hasMatchingIndex = !isMounting && matchingIndex === skewedIndex;
 			if (isMounting) {
 				if (matchingIndex == -1) {
 					skew--;
 				}
-			} else if (!hasMatchingIndex) {
+			} else if (matchingIndex !== skewedIndex) {
 				if (matchingIndex === skewedIndex + 1) {
 					skew++;
 					hasMatchingIndex = true;
@@ -186,11 +183,11 @@ export function diffChildren(
 			}
 
 			skewedIndex = i + skew;
-			if (matchingIndex == i && !isMounting) {
-				hasMatchingIndex = true;
-			}
+			hasMatchingIndex =
+				hasMatchingIndex || (matchingIndex == i && !isMounting);
 
 			if (
+				!isHydrating &&
 				!isMounting &&
 				typeof childVNode.type == 'function' &&
 				(matchingIndex !== skewedIndex ||