### Tested versions

Godot Engine v4.2.stable.official.46dc27791

### System information

Windows 10

### Issue description

When exporting to web, Godot fails with this error in the console:

> scene/main/window.cpp:884 - Attempting to make child window exclusive, but the parent window already has another exclusive child. This window: /root/@<!-- -->EditorNode@<!-- -->17120/@<!-- -->Panel@<!-- -->13/@<!-- -->ProjectExportDialog@<!-- -->559/@<!-- -->VBoxContainer@<!-- -->137/@<!-- -->AcceptDialog@<!-- -->411, parent window: /root/@<!-- -->EditorNode@<!-- -->17120/@<!-- -->Panel@<!-- -->13/@<!-- -->ProjectExportDialog@<!-- -->559, current exclusive child window: /root/@<!-- -->EditorNode@<!-- -->17120/@<!-- -->Panel@<!-- -->13/@<!-- -->ProjectExportDialog@<!-- -->559/@<!-- -->ProgressDialog@<!-- -->17444

![a](https://github.com/godotengine/godot/assets/2000051/bf9d22aa-d3fe-4e11-bff6-c387e740fe90)

This happens for newly created empty projects.


### Steps to reproduce

1. Open the attached project (or create a new project).
2. Project->Export->Export All
3. Observe the console error.  No output files are generated.


### Minimal reproduction project (MRP)

[export_test.zip](https://github.com/godotengine/godot/files/13574810/export_test.zip)

if (f.is_null()) {
			DirAccess::remove_file_or_error(tmppath);
			add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), vformat(TTR("Can't open file for writing at path \"%s\"."), p_path));
			return ERR_CANT_CREATE;
		}
	} else {
		
		f = FileAccess::open(p_path, FileAccess::READ_WRITE);
		if (f.is_null()) {
			DirAccess::remove_file_or_error(tmppath);
			add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), vformat(TTR("Can't open file for reading-writing at path \"%s\"."), p_path));
			return ERR_FILE_CANT_OPEN;
		}
		f->seek_end();
		embed_pos = f->get_position();
		if (r_embedded_start) {
			*r_embedded_start = embed_pos;
		}
		
		int pad = f->get_position() % 8;
		for (int i = 0; i < pad; i++) {
			f->store_8(0);
		}
	}
	int64_t pck_start_pos = f->get_position();
	f->store_32(PACK_HEADER_MAGIC);
	f->store_32(PACK_FORMAT_VERSION);
	f->store_32(VERSION_MAJOR);
	f->store_32(VERSION_MINOR);
	f->store_32(VERSION_PATCH);