### 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
if (is_member) {
					target = member; 
				} else {
					target = _parse_expression(codegen, r_error, assignment->assignee);
					if (r_error) {
						return GDScriptCodeGenerator::Address();
					}
				}
				GDScriptCodeGenerator::Address assigned_value = _parse_expression(codegen, r_error, assignment->assigned_value);
				if (r_error) {
					return GDScriptCodeGenerator::Address();
				}
				GDScriptCodeGenerator::Address to_assign;
				bool has_operation = assignment->operation != GDScriptParser::AssignmentNode::OP_NONE;
				if (has_operation) {
					
					GDScriptCodeGenerator::Address op_result = codegen.add_temporary(_gdtype_from_datatype(assignment->get_datatype(), codegen.script));
					GDScriptCodeGenerator::Address og_value = _parse_expression(codegen, r_error, assignment->assignee);
					gen->write_binary_operator(op_result, assignment->variant_op, og_value, assigned_value);
					to_assign = op_result;
					if (og_value.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
						gen->pop_temporary();
					}
				} else {
					to_assign = assigned_value;
				}
				if (has_setter && !is_in_setter) {
					
					Vector<GDScriptCodeGenerator::Address> args;
					args.push_back(to_assign);