Can't open URL with gx after opening vim session #20934

Steps to reproduce

1. Create a text file url.txt containing a website URL, e.g. https://www.vim.org
2. Move the cursor over the URL and press gx to open it in your browser
3. Create a session file with :mks!
4. Exit vim and re-open it with vim -S
5. Move the cursor over the URL and press gx and get the error messages:

E117: Unknown function: GetWordUnderCursor                                        
E116: Invalid arguments for function dist#vim9#Open

Expected behaviour

The gx command should open the URL no matter if vim is running a session or not.

Version of Vim

9.2.900

Environment

macOS 26.5.2
Terminal / xterm 2.15
zsh 5.9 (arm64-apple-darwin25.0)

and

Fedora Linux 44 (Workstation Edition)
Termial / ptyxis 50.1
bash 5.3.9