[Bug]: Share not found error when creating a federated share from a share

[kesselb]

Bug description

Creating a federated share with a user on a remote instance leads to a "Share not found" error when the node to be shared is a share itself.

Screencast.From.2026-01-30.17-56-46.mp4

Steps to reproduce

1. Alice: Create a folder "Test 1" and share it with Bob
2. Bob: Re-share folder "Test 1" with John (on a different nextcloud instance)
3. See the "Share not found" toast

Expected behavior

No error

Nextcloud Server version

master, 33, 32, 31