dict2inst does not work on classes with _init parameters

[ducklin5]

Godot version:
Godot Engine v3.1.1.stable.official

Issue description:
dict2inst does not work on classes with _init parameters. A simple fix is to manually initialize the object after it has been created with .new()

Steps to reproduce:
Create a scene with an external(not built in script). Then run the scene with this in the script:

extends Node2D

class A:
	var value 
	func _init(val):
		self.value = val
		
class B:
	var value
	func init(val):
		self.value = val

func serializeA():
	var inst = A.new(1)
	var instDict = inst2dict(inst)
	var inst2 = dict2inst(instDict)
	print("A was serialized and deserialize succesfully")

func serializeB():
	var inst = B.new()
	B.init(1)
	var instDict = inst2dict(inst)
	var inst2 = dict2inst(instDict)
	print("B was serialized and deserialize succesfully")

func _ready():
	serializeA() # this will crash the program
	serializeB() # this runs fine

[ducklin5]

Just found an alternative fix:

class A:
	var value 
	func _init(val=0):
		self.value = val

I'm guessing the reason for the crash is that dict2inst uses .new() without any parameters. I think the easiest solution to this is to make note of this in the docs

[Reneator]

There is a kind of similar problem with bytes2var where a node would not work properly if it has an _init() method with an argument defined.

If i remove the custom _init() method it works fine.

[I-Have-No-Idea-What-IAmDoing]

seems to not be fixed in v3.4.2 as I just ran into this issue was able to go around it by making the parameter have default values but the error that is given is misleading.

[kleonc]

Confirmed, still happens in 3.5.1.stable. Works fine in master.

Changes done in #32534 were never backported to 3.x.

[vnen]

That is sort of expected, dict2inst() won't be able to create an instance of a class that does not have a default constructor. We may find a way to bypass the constructor since the state is saved, but it isn't really a simple thing to do.