Assigning a Variant with value freed object to non-Variant causes error

[allimehcla]

Tested versions

26.3.alpha 1

System information

Redot v26.3.alpha.1 (957fda4) - CachyOS Linux

Issue description

I saw #1311 addressed the freed object issue with containers that has been reported in #1310 and godotengine/godot#110511. So I was wondering if we plan to address a similar issue in godotengine/godot#85947 when assigning a Variant with value freed object to non-Variant. There is a PR godotengine/godot#87296 to address it but it is not merged.

I am not familiar with the Godot or Redot codebase (nor I have written a line of CPP before) but I saw this proposal completed a few days ago: godotengine/godot-proposals#12323 (comment)

var node2d: Node2D = Node2D.new()
node2d.free()

var node: Node = node2d # OK

var variant: Variant = node2d # OK
node = variant # Trying to assign invalid previously freed instance.

var node := Node.new()
var dict := { "node": node }
node.free()

node = dict["node"] # Trying to assign invalid previously freed instance.

The following cases are not the same but they have a similar issue.

var node := Node.new()
node.free()

typed(node)  # Invalid type in function 'typed' in base 'Node2D (main.gd)'. The Object-derived class of argument 1 (previously freed) is not a subclass of the expected argument class.

func typed(node: Node) -> void:
	pass

var obj := Object.new()
print(obj is Object)
obj.free()
print(obj is Object) # Left operand of 'is' is a previously freed instance.

This case doesn't halt execution but it does emit an error.

var node := Node.new()
var lambda = func(): print(node)
node.free()
lambda.call() # Prints `<null>` but has error "Lambda capture at index 0 was freed. Passed "null" instead."

I think this one is just similar to typed function case.

var node := Node.new()
var lambda = func(node: Node): print(node)
node.free()
lambda.call(node) # Invalid type in function '<anonymous lambda>(lambda) (Callable)'. The Object-derived class of argument 1 (previously freed) is not a subclass of the expected argument class.
lambda.bind(node).call() # Invalid type in function '<anonymous lambda>(lambda) (Callable)'. The Object-derived class of argument 1 (previously freed) is not a subclass of the expected argument class.

Steps to reproduce

Same as provided codeblock

Minimal reproduction project (MRP)

Same as provided codeblock