### 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
Vector<GDScriptCodeGenerator::Address> args;
							args.push_back(assigned);
							GDScriptCodeGenerator::Address call_base = is_static ? GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::CLASS) : GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::SELF);
							gen->write_call(GDScriptCodeGenerator::Address(), call_base, member_property_setter_function, args);
						} else if (is_static) {
							GDScriptCodeGenerator::Address temp = codegen.add_temporary(static_var_data_type);
							gen->write_assign(temp, assigned);
							gen->write_set_static_variable(temp, static_var_class, static_var_index);
							gen->pop_temporary();
						} else {
							gen->write_assign(target_member_property, assigned);
						}
						if (!known_type) {
							gen->write_end_jump_if_shared();
						}
					}
				}
				if (assigned.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					gen->pop_temporary();
				}
			} else if (assignment->assignee->type == GDScriptParser::Node::IDENTIFIER && _is_class_member_property(codegen, static_cast<GDScriptParser::IdentifierNode *>(assignment->assignee)->name)) {
				
				GDScriptCodeGenerator::Address assigned_value = _parse_expression(codegen, r_error, assignment->assigned_value);
				if (r_error) {
					return GDScriptCodeGenerator::Address();
				}
				GDScriptCodeGenerator::Address to_assign = assigned_value;
				bool has_operation = assignment->operation != GDScriptParser::AssignmentNode::OP_NONE;
				StringName name = static_cast<GDScriptParser::IdentifierNode *>(assignment->assignee)->name;
				if (has_operation) {