Warning emitted when opening any project: "Attempting to access theme items too early; prefer NOTIFICATION_POSTINITIALIZE and NOTIFICATION_THEME_CHANGED"

[akien-mga]

Godot version

4.1.dev (240ed28)

System information

Mageia 9, Linux

Issue description

Since a few days, I've seen this warning show up in the console when editing a project with Godot 4.1.dev:

WARNING: Attempting to access theme items too early; prefer NOTIFICATION_POSTINITIALIZE and NOTIFICATION_THEME_CHANGED
     at: get_theme_icon (scene/gui/control.cpp:2433)

It doesn't happen in 4.1.dev1 (db13026), so it's a recent regression introduced between db13026 and 240ed28.

Steps to reproduce

• Create new project
• Open it
• Check console

Minimal reproduction project

n/a