### Godot version

v4.0.3.stable.official [5222a99f5]
Master [6101240231600c871f5c5473872532c68ea3268c] (confirmed by https://github.com/godotengine/godot/issues/77666#issuecomment-1568952502)

### System information

Window 10

### Issue description

References are not unreferenced at the end of `if` scopes.

### Steps to reproduce

Copy, paste and run the snippet below, check the results:

```gdscript
extends Node


func _ready() -> void:
  var ref := RefCounted.new()
  var ref_count : int

  # OK
  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # OK
  if true:
    var temp := ref
    temp = null

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # FAIL
  if true:
    var temp := ref

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)
```

Output example:

```
Expected: 1, Result: 1
Expected: 1, Result: 1
Expected: 1, Result: 2
```

### Minimal reproduction project

N/A
struct ChainInfo {
					bool is_named = false;
					GDScriptCodeGenerator::Address base;
					GDScriptCodeGenerator::Address key;
					StringName name;
				};
				List<ChainInfo> set_chain;
				for (List<const GDScriptParser::SubscriptNode *>::Element *E = chain.back(); E; E = E->prev()) {
					if (E == chain.front()) {
						
						break;
					}
					const GDScriptParser::SubscriptNode *subscript_elem = E->get();
					GDScriptCodeGenerator::Address value = codegen.add_temporary(_gdtype_from_datatype(subscript_elem->get_datatype(), codegen.script));
					GDScriptCodeGenerator::Address key;
					StringName name;
					if (subscript_elem->is_attribute) {
						name = subscript_elem->attribute->name;
						gen->write_get_named(value, name, prev_base);
					} else {
						key = _parse_expression(codegen, r_error, subscript_elem->index);
						if (r_error) {
							return GDScriptCodeGenerator::Address();
						}
						gen->write_get(value, key, prev_base);
					}
					
					set_chain.push_front({ subscript_elem->is_attribute, prev_base, key, name }); 
					prev_base = value;
				}