### Godot version

4.0 stable

### System information

Fedora, RX 590

### Issue description

I made a dictionary, and instead of using `:` to separate between key and value, i accidentally used `=`.
The error message was not clear at all `Parse Error: Expected identifier or string as LUA-style dictionary key.` 

I don't think assuming that people know how dictionaries are made in LUA is reasonable. And if this is not about LUA the programming language, i don't even know what this is about :D

I think this error should be replaced with something of the sort "Please use `:` as separator instead of `=` in your dictionary"

### Steps to reproduce

Paste this code in a script:

```

var dict = {
	1 = "lala"
}
```

Observe the error message
![image](https://user-images.githubusercontent.com/7917475/224549538-38ea25aa-ba75-431e-868b-0733a53b90ad.png)


### Minimal reproduction project

see above
if (p_get_node->use_dollar) {
		push_text("$");
	}
	push_text(p_get_node->full_path);
}
void GDScriptParser::TreePrinter::print_identifier(IdentifierNode *p_identifier) {
	if (p_identifier != nullptr) {
		push_text(p_identifier->name);
	} else {
		push_text("<invalid identifier>");
	}
}
void GDScriptParser::TreePrinter::print_if(IfNode *p_if, bool p_is_elif) {