Fail to open a node script from Godot Tools Scene Preview

### Godot version

v4.6.2.stable.arch_linux [001aa128b]

### VS Code version

VSCodium 1.112.01907

### Godot Tools VS Code extension version

2.6.1

### System information

Linux 6.19.10-1-cachyos (Hyprland 0.54.3 - Wayland)

### Issue description

When trying to open a node script from the Godot Tool Scene Preview, I get an error :
Error running command godotTools.scenePreview.openScript: Cannot read properties of undefined (reading 'substring'). This is likely caused by the extension that contributes godotTools.scenePreview.openScript.

Both Godot and VSCodium have that scene loaded. The game is not running.

Opening the script through the Project Explorer works fine.

### Steps to reproduce

1. Open Godot and VSCodium.
2. In VSCodium, go to a scene tree in the Godot Toos : Scene Preview.
3. Select the "script" icon next to a node.