### Godot version

v4.0.rc1.official [8843d9ad3]

### System information

Lubuntu

### Issue description

You can't use + or += to mutate typed arrays.

It seems to be not correctly getting the type information from the second operand.

An erudite poster on the discord puts it differently:
> it's more like operator + doesn't retain Array typing
> the syntax for Array Concatenation via operators, but the idea gets across i think


The error you see is:
```Trying to assign an array of type "Array" to a variable of type "Array[int]".```


### Steps to reproduce

```
	var Alice: Array[int] = [1,2,3]
	var Bob: Array[int] = [4,5,6]
	Alice += Bob
```
This will crash with the above error message.

### Minimal reproduction project

[plus_syntax_broken_demo_project.zip](https://github.com/godotengine/godot/files/10694514/plus_syntax_broken_demo_project.zip)

bool is_valid = false;
		Variant value = base_value.get(index_value, &is_valid);
		if (is_valid) {
			is_reduced = true;
			return value;
		} else {
			return Variant();
		}
	}
}
Array GDScriptAnalyzer::make_array_from_element_datatype(const GDScriptParser::DataType &p_element_datatype, const GDScriptParser::Node *p_source_node) {
	Array array;
	if (p_element_datatype.builtin_type == Variant::OBJECT) {
		Ref<Script> script_type = p_element_datatype.script_type;
		if (p_element_datatype.kind == GDScriptParser::DataType::CLASS && script_type.is_null()) {
			Error err = OK;
			Ref<GDScript> scr = GDScriptCache::get_shallow_script(p_element_datatype.script_path, err);
			if (err) {
				push_error(vformat(R"(Error while getting cache for script "%s".)", p_element_datatype.script_path), p_source_node);
				return array;
			}
			script_type.reference_ptr(scr->find_class(p_element_datatype.class_type->fqcn));
		}
		array.set_typed(p_element_datatype.builtin_type, p_element_datatype.native_type, script_type);
	} else {
		array.set_typed(p_element_datatype.builtin_type, StringName(), Variant());
	}
	return array;
}
Variant GDScriptAnalyzer::make_variable_default_value(GDScriptParser::VariableNode *p_variable) {