Revert "Always return the sibling cursor from element diffs"

This reverts commit 6df9a00.

Author: JoviDeCroock

src/diff/children.js

@@ -141,7 +141,7 @@ export function diffChildren(
 			if (oldVNode._dom) {
 				oldVNode._dom = NULL;
 			}
-		} else if (result !== UNDEFINED) {
+		} else if (typeof childVNode.type == 'function' && result !== UNDEFINED) {
 			oldDom = result;
 		} else if (newDom) {
 			oldDom = newDom.nextSibling;

src/diff/index.js

@@ -72,7 +72,7 @@ export function diff(
 
 	// When passing through createElement it assigns the object
 	// constructor as undefined. This to prevent JSON-injection.
-	if (newVNode.constructor !== UNDEFINED) return UNDEFINED;
+	if (newVNode.constructor !== UNDEFINED) return NULL;
 
 	// If the previous diff bailed out, resume creating/hydrating.
 	if (
@@ -426,7 +426,7 @@ export function diff(
 			options._catchError(e, newVNode, oldVNode);
 		}
 	} else {
-		oldDom = (newVNode._dom = diffElementNodes(
+		oldDom = newVNode._dom = diffElementNodes(
 			oldVNode._dom,
 			newVNode,
 			oldVNode,
@@ -437,7 +437,7 @@ export function diff(
 			isHydrating,
 			refQueue,
 			parentDom
-		)).nextSibling;
+		);
 	}
 
 	if ((tmp = options.diffed)) tmp(newVNode);