Bug description

When the project is exported to Web, running the game only shows the GUI. When exported to Windows or Linux, the game don't open.

Steps to reproduce

1. Create a game with a room with props and a character.
2. Run the game in the Editor. It should work as expected.
3. Export the project to Web, Windows, or Linux.
4. Running the game on the Web build will make the GUI visible, but nothing else. When trying to open the .exe or the .x86_64 nothing happens.

Expected vs observed behavior

The exported project should work as it does in the Editor.

Environment information (please complete):

• OS type and version: Windows 11
• Godot version: 4.2.1
• Plugin version or branch: Beta 2

Additional context

The following error message appears in the Output when exporting: res://addons/popochiu/popochiu_export_plugin.gd:67 - Cannot call method 'file_exists' on a null value.