Crash running project when using `ProjectSettings.load_resource_pack` in autoload

[yukinogatari]

Tested versions

Not reproducible in: v4.4.1.stable.official [49a5bc7], v4.5.dev1.official [97241ff], v4.5.dev2.official [af2c713]

Reproducible in: v4.5.dev3.official [55fc6e73f], v4.5.dev4.official [209a446], v4.5.dev5.official [64b0990], v4.5.beta1.official [46c495c]

System information

Godot v4.5.beta1 - Windows 10 (build 19045) - Multi-window, 2 monitors - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 3070 (NVIDIA; 32.0.15.6636) - AMD Ryzen 9 7900X 12-Core Processor (24 threads) - 31.11 GiB memory

Issue description

Calling ProjectSettings.load_resource_pack from the _init routine of an autoload causes Godot to be unable to find the project's main scene and immediately crash on startup.

Just before the crash, Godot outputs this to the console (and only the console):

Loading resource: res://uid:/ghi10vng2cd7
Failed loading resource: res://uid:/ghi10vng2cd7
ERROR: Resource file not found: res://uid:/ghi10vng2cd7 (expected type: unknown)
   at: (core/io/resource_loader.cpp:351)
ERROR: Failed loading scene: res://uid:/ghi10vng2cd7.
   at: (main/main.cpp:4526)

Where ghi10vng2cd7 is the UID of the main scene.

Running the scene in isolation works without issue, and calling load_resource_pack slightly later (such as in _ready) also allows the project to start up normally. I have not done any further testing, such as how it behaves when the pck file specified actually exists (but in this case, it not existing is intentional).

Steps to reproduce

1. Run the MRP in v4.5.beta1.official [46c495c], crash
2. Remove the _init function from autoload.gd, no crash

Minimal reproduction project (MRP)

4.5-crash.zip

[precup]

The behavior difference bisects to #105288, CCing @bruvzg for context.