The `_create_instance: Error constructing a GDScriptInstance.`  error happens when GDscript fails to construct an object for some reason. 

Usually, that reason is that you have an object with an overwritten `_init()`  function, like so:

And then you try to create that object in the editor's inspector. The issue here is that you can't specify the `_init` parameter values in the editor. 

1. Add default values to the `_init` parameters

2. Remove the custom `_init` and rely on exported values instead

How to solve " Error constructing a GDScriptInstance." in GDScript - Godot 4

Here's how to create a timer along with different options in GDScript:

How to create and connect a Timer in GDScript - Godot 4

Here are the different ways to access nodes in GDScript:

To enable "Access as unique name" for a node, right click on it in the inspector and select "Access as unique name". A percentage sign will appear next to it in the inspector.

How to access nodes in GDScript - Godot 4

Signal can be connected through the editor, but it's also useful to know how to connect signal in GDScript. 

How to solve " Error constructing a GDScriptInstance." in GDScript - Godot 4

How to create and connect a Timer in GDScript - Godot 4

How to access nodes in GDScript - Godot 4

How to connect a signal in GDScript - Godot 4