core-app-api: tweak path property check in v2 traversal

Co-authored-by: blam <ben@blam.sh>
Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/core-app-api/src/routing/collectors.tsx

@@ -109,7 +109,7 @@ export const routingV2Collector = createCollector(
 
     const parentChildren = ctx?.obj?.children ?? acc.objects;
 
-    if (pathProp) {
+    if (pathProp !== undefined) {
       if (typeof pathProp !== 'string') {
         throw new Error(
           `Element path must be a string at "${stringifyNode(node)}"`,