GetNode<Timer>("/root/Main/StartTimer") giving System.InvalidCastException - godot

Question

I'm doing the "Your First 2D Game" in Godot because I'm a beginner. I used C# as my script language.
I'm having a problem with GetNode("/root/Main/StartTimer") giving to me a System.InvalidCastException: Specified cast is not valid.
But, StartTimer is the Timer type. So, There's no way it could launch this exception.
I'm exactly at this page of the tutorial:
https://docs.godotengine.org/en/stable/getting_started/first_2d_game/05.the_main_game_scene.html
public void New_Game()
{
Score = 0;
var player = GetNode<Player>("/root/Main/Player");
var startPosition = GetNode<Position2D>("/root/Main/StartPosition");
player.Start(startPosition.Position);
GetNode<Timer>("/root/Main/StartTimer").Start();
}
Well, I don't know what to do, since I'm following the tutorial. I think it shouldn't happen because StartTimer is the type Timer, screenshot below:
These are all my scripts:
Main.cs script:
using Godot;
using System;
public class Main : Node
{
// Declare member variables here. Examples:
// private int a = 2;
// private string b = "text";
#pragma warning disable 649
[Export]
public PackedScene MobScene;
#pragma warning restore 649
public int Score;
// Called when the node enters the scene tree for the first time.
public override void _Ready()
{
GD.Randomize();
New_Game();
}
// // Called every frame. 'delta' is the elapsed time since the previous frame.
// public override void _Process(float delta)
// {
//
// }
public void Game_Over()
{
GetNode<Timer>("MobTimer").Stop();
GetNode<Timer>("ScoreTimer").Stop();
}
public void New_Game()
{
Score = 0;
var player = GetNode<Player>("/root/Main/Player");
var startPosition = GetNode<Position2D>("/root/Main/StartPosition");
player.Start(startPosition.Position);
GetNode<Timer>("/root/Main/StartTimer").Start();
//Timer StartTimer = GetNode<Timer>("/root/Main/StartTimer");
}
public void OnScoreTimerTimeout()
{
Score++;
}
public void OnStartTimerTimeout()
{
GetNode<Timer>("MobTimer").Start();
GetNode<Timer>("ScoreTimer").Start();
}
public void OnMobTimerTimeout()
{
//Create a new instance of the Mob Scene
var mob = (Mob)MobScene.Instance();
//Choose a random Location on Path2D
var mobSpawnLocation = GetNode<PathFollow2D>("MobPath/MobSpawnLocation");
mobSpawnLocation.Offset = GD.Randi();
//Set the mon's direction perpendicular to the path direction.
float direction = mobSpawnLocation.Rotation + Mathf.Pi / 2;
//Set the mob's position to a random location.
mob.Position = mobSpawnLocation.Position;
//Add some randomness to the direction
direction += (float)GD.RandRange(-Mathf.Pi / 4, Mathf.Pi / 4);
mob.Rotation = direction;
// Choose the velocity.
var velocity = new Vector2((float)GD.RandRange(150.0, 250.0), 0);
mob.LinearVelocity = velocity.Rotated(direction);
// Spawn the mob by adding it to the Main scene.
AddChild(mob);
}
}
Mobs.cs script:
using Godot;
using System;
public class Mob : RigidBody2D
{
// Declare member variables here. Examples:
// private int a = 2;
// private string b = "text";
// Called when the node enters the scene tree for the first time.
public override void _Ready()
{
var animSprite = GetNode<AnimatedSprite>("AnimatedSprite");
animSprite.Playing = true;
string[] mobTypes = animSprite.Frames.GetAnimationNames();
animSprite.Animation = mobTypes[GD.Randi() % mobTypes.Length];
}
// // Called every frame. 'delta' is the elapsed time since the previous
frame.
// public override void _Process(float delta)
// {
//
// }
public void OnVisibilityNotifier2DScreenExited()
{
QueueFree();
}
}
Player.cs script:
using Godot;
using System;
public class Player : Area2D
{
// Declare member variables here. Examples:
// private int a = 2;
// private string b = "text";
//How fast the player will move (pixel/sec).
[Export]
public int Speed = 400;
[Signal]
public delegate void Hit();
// Size of the game window.
public Vector2 ScreenSize;
// Called when the node enters the scene tree for the first time.
public override void _Ready()
{
ScreenSize = GetViewportRect().Size;
Hide(); //Player is hidden when the game starts
}
// Called every frame. 'delta' is the elapsed time since the previous
frame.
public override void _Process(float delta)
{
var velocity = Vector2.Zero; //Tha Player's movement vector
if (Input.IsActionPressed("move_right"))
{
velocity.x += 1;
}
if (Input.IsActionPressed("move_left"))
{
velocity.x -= 1;
}
if (Input.IsActionPressed("move_down"))
{
velocity.y += 1;
}
if (Input.IsActionPressed("move_up"))
{
velocity.y -= 1;
}
var animatedSprite = GetNode<AnimatedSprite>("AnimatedSprite");
if (velocity.Length() > 0)
{
velocity = velocity.Normalized() * Speed;
animatedSprite.Play();
}
else
{
animatedSprite.Stop();
}
Position += velocity * delta;
Position = new Vector2(
x: Mathf.Clamp(Position.x, 0, ScreenSize.x),
y: Mathf.Clamp(Position.y, 0, ScreenSize.y)
);
if (velocity.x != 0)
{
animatedSprite.Animation = "walk";
animatedSprite.FlipV = false;
animatedSprite.FlipH = velocity.x < 0; //Here I'm doing a boolean
test
}
else if (velocity.y != 0)
{
animatedSprite.Animation = "up";
animatedSprite.FlipV = velocity.y > 0; //Here I'm doing a boolean
test
}
}
public void On_Player_Body_Entered(PhysicsBody2D body)
{
Hide(); //Player disappears after being hit.
EmitSignal(nameof(Hit));
//Must be deferred as we can't change physics properties on a physics
callback.
GetNode<CollisionShape2D>("CollisionShape2D").SetDeferred("disabled",
true);
}
//Reset the player when starting the game
public void Start(Vector2 pos)
{
Position = pos;
Show();
GetNode<CollisionShape2D>("CollisionShape2D").Disabled = false;
}
}
If you can help me, please.. I'd be very glad and thankful if you could! Thank you!

Answer 1

The reason your game crashes is because of the main.cs script that is attached to all timer nodes.
Since the main.cs script extends the Node object all your timers are becoming Node objects instead of Timer objects. And because Node objects do not have a Start() function your game crashes.
The simple solution to this is to detach the main script from all nodes but the main node.
As Bugfish pointed out, Godot must not attach a script to a node when you connect a signal. Especially not a script from another node. After you deleted your main script from the timers, I recommend to go through the process of signal connection again just to figure out what went wrong the first time.