### Godot version

4.0 -> latest

**I've tested all this versions:**
4.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4
4.1, 4.1.1
4.2 dev 4

in all this versions problem exists.

### System information

Fedora 38, macOS

### Issue description

I have found a very strange bug while generating translations. The presence of a method modifying the dictionary's content causes the editor to crash during the generation of the translation template.

The mere presence of an uninvoked method causes a crash.

**Edit: The issue occurs not only with singletons. Any script containing a method that modifies any dictionary leads to a crash.**

### Steps to reproduce

**Project -> Project Settings -> Localizations -> Generate POT -> Add (Add your singleton)**

```
extends Node

var session_data = {
	"coins" : 0,
	"power": 0
}

var shop_items = [
	{
		"id": "max_hp",
		"name": tr("First Shop Item"),
		"desc": tr("Great tool."),
	}
]

func add_power(val: int):
	session_data["power"] += val
```

_⚠️ Problem is in add_power method, not in shop_items._


**Project -> Project Settings -> Localizations -> Generate POT -> Generate**

And... Crash.


[Nagranie ekranu z 2023-09-14 13-10-42.webm](https://github.com/godotengine/godot/assets/5132385/6a00805a-34c8-408e-9b00-eb5875301312)



### Minimal reproduction project

[translation_gm_crash.zip](https://github.com/godotengine/godot/files/12104763/translation_gm_crash.zip)

_Just open project and go to: Project -> Project Settings -> Localizations -> Generate POT -> Generate_

_assess_expression(while_node->condition);
				_traverse_block(while_node->loop);
				break;
			}
			case GDScriptParser::Node::MATCH: {
				const GDScriptParser::MatchNode *match_node = static_cast<const GDScriptParser::MatchNode *>(statement);
				_assess_expression(match_node->test);
				for (int j = 0; j < match_node->branches.size(); j++) {
					_traverse_block(match_node->branches[j]->block);
				}
				break;
			}
			case GDScriptParser::Node::RETURN:
				_assess_expression(static_cast<const GDScriptParser::ReturnNode *>(statement)->return_value);
				break;
			case GDScriptParser::Node::ASSERT:
				_assess_expression((static_cast<const GDScriptParser::AssertNode *>(statement))->condition);
				break;
			case GDScriptParser::Node::ASSIGNMENT:
				_assess_assignment(static_cast<const GDScriptParser::AssignmentNode *>(statement));
				break;
			default:
				if (statement->is_expression()) {
					_assess_expression(static_cast<const GDScriptParser::ExpressionNode *>(statement));
				}
				break;
		}
	}
}
void GDScriptEditorTranslationParserPlugin::_assess_expression(const GDScriptParser::ExpressionNode *p_expression) {