Tween Error "started with no tweeners"

[lucaworo]

Godot Version

4.2.1

Question

I took the following code for a textbox from a tutorial and I’m getting an error. I don’t have much knowledge about tweens yet.
Can someone help me?

Error: started with no tweeners

extends CanvasLayer

const CHAR_READ_RATE = 0.05

@onready var textbox_container = $TextboxContainer
@onready var start_symbol = $TextboxContainer/MarginContainer/HBoxContainer/Start
@onready var end_symbol = $TextboxContainer/MarginContainer/HBoxContainer/End
@onready var label = $TextboxContainer/MarginContainer/HBoxContainer/Label
@onready var tween = get_tree().create_tween()

enum State {
READY,
READING,
FINISHED
}

var current_state = State.READY
var text_queue =

func _ready():
hide_textbox()
queue_text(“Test”)
queue_text(“Hallo!!”)
queue_text(“Hier ist ein sehr langer Beispieltext, um zu schauen ob der Textumbruch funktioniert”)

func _process(_delta):
match current_state:
State.READY:
if !text_queue.is_empty():
display_text()
State.READING:
if Input.is_action_just_pressed(“ui_cancel”):
tween.kill()
label.visible_characters = - 1.0
end_symbol.text = “>”
change_state(State.FINISHED)
State.FINISHED:
if Input.is_action_just_pressed(“ui_cancel”):
change_state(State.READY)
hide_textbox()

func queue_text(next_text):
text_queue.push_back(next_text)

func hide_textbox():
start_symbol.text = “”
end_symbol.text = “”
label.text = “”
textbox_container.hide()

func show_textbox():
start_symbol.text = “*”
textbox_container.show()

func display_text():
tween = get_tree().create_tween()
var next_text = text_queue.pop_front()
label.text = next_text
label.visible_characters = 0.0
change_state(State.READING)
show_textbox()
tween.tween_property(label, “visible_characters”, len(next_text), len(next_text) * CHAR_READ_RATE).from(0)
tween.connect(“finished”, on_tween_finished)
end_symbol.text = “…”

func on_tween_finished():
end_symbol.text = “>”
change_state(State.FINISHED)

func change_state(next_state):
current_state = next_state

[herrspaten]

Apparently if you create a tween as you do with onready, but dont use it, it throws this error, since it doesnt have anything to do

[lucaworo]

If I remove the line, an error occurs.
Line 33: tween.kill()
It can’t find a tween in the function.

[herrspaten]

it tries to kill a tween that doesnt exist. Try doing this:

var tween: Tween
.
.
. # line 33
if tween != null:
    tween.kill()

[lucaworo]

The same Error

[herrspaten]

replace “tween != null” with “tween.is_valid()”

[lucaworo]

Once again the same error

[gertkeno]

I think you’ll need both actually.

if is_instance_valid(tween) and tween.is_valid(): # how valid can you get lol
    tween.kill()

[militaryg]

what about:

if tween:
    tween.kill()

usually if it’s empty it won’t go through or null

[gertkeno]

Usually that is equivalent to

if tween != null:
    tween.kill()

I would love if it was a special case for tween though

[militaryg]

not sure why but for data like:

var data = 0
var data1 =  ""

if data:
    pass
if data1:
    pass

it won’t go through this 2 if statements this 2 datas aint null but are “emtpy”

[gertkeno]

In that case int, float, and I think string can’t be null. int is implicitly data > 0 like in C/C++ and string is implicitly not data1.is_empty().

[lucaworo]

The error is still there despite the changes. The scene runs smoothly, but the error keeps occurring.

[gertkeno]

What is the error exactly? Are we getting the wrong line, I’m thinking this is for the “ui_cancel” action

[lucaworo]

I added the left mouse button and placed it there. The error still occurs.

[gertkeno]

It shouldn’t be the same error at this point, did you change the definition like @herrspaten said?

# was: @onready var tween = get_tree().create_tween()
var tween: Tween

[lucaworo]

It works! Thank you very much for the help