### Godot version

4.1.dev

### System information

Win11

### Issue description

I load a non-existing GDScript, but it still returns a valid instance instead of null.
```gdscript
@tool
extends EditorScript

func _run():
	var s = ResourceLoader.load("non_exists.gd", "", ResourceLoader.CACHE_MODE_IGNORE)
	print(s)
	assert(s == null)

```

```
  Attempt to open script 'res://non_exists.gd' resulted in error 'File not found'.
<GDScript#-9223369015982753437>
  res://new_script.gd:7 - Assertion failed.

```

### Steps to reproduce

N/A

### Minimal reproduction project

N/A
"as",
		"assert",
		"await",
		"breakpoint",
		"class",
		"class_name",
		"extends",
		"is",
		"func",
		"preload",
		"signal",
		"super",
		
		"const",
		"enum",
		"static",
		"var",
		
		"break",
		"continue",
		"if",
		"elif",
		"else",
		"for",
		"pass",
		"return",
		"match",
		"while",