https://docs.godotengine.org/en/stable/tutorials/scripting/gdscript/warning_system.html
GDScript warning system — Godot Engine (stable) documentation in English
The GDScript warning system complements static typing(but it can work without static typing too). It's here to help you avoid mistakes that are hard to spot...
gdscript warning systemgodot enginestabledocumentationenglish