`Lua: Export Document ...` fails, throws error in log when trying to export documentation.

まだ誰も着手していません。

### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

Windows

### What is the issue affecting?

Other

### Expected Behaviour

Export document to allow exporting documentation.

### Actual Behaviour

Nothing happens, though if you check the logs there is the following error:

```
[20:31:45.883][error][#0]: script\cli\doc.lua:287: bad argument #1 to 'path' (bee::path expected, got nil)
stack traceback:
[C]: in function 'bee.filesystem.path'
script\cli\doc.lua:287: in upvalue 'collectConfig'
script\cli\doc.lua:300: in function 'cli.doc.export'
script\cli\doc.lua:354: in function 'cli.doc.makeDoc'
script\core\command\exportDocument.lua:11: in function 'core.command.exportDocument'
script\provider\provider.lua:984: in function
[C]: in function 'xpcall'
script\proto\proto.lua:200: in function
```

### Reproduction steps

1. Open Command Pallete
2. Select `Lua: Export Document ...`
3. Select a location to export to.
4. Observe as nothing is output, and the error is thrown in the log.

### Additional Notes

_No response_

### Log File

[file_d%3A_Desktop_MMC_MultiMC_instances_pathfinding_.minecraft_saves_world_computercraft_computer_1_Simplify-Mapping.log](https://github.com/LuaLS/lua-language-server/files/15281399/file_d.3A_Desktop_MMC_MultiMC_instances_pathfinding_.minecraft_saves_world_computercraft_computer_1_Simplify-Mapping.log)

Lua: Export Document コマンドで失敗を再現し、script/cli/doc.lua:287 の collectConfig から開始してください。script/core/command/exportDocument.lua からの呼び出しを追ってください。提供されたログとエクスポートパスの処理を確認してください。出力先を選択すると、ログに記録されたエラーなしでドキュメントが生成されれば完了です。

索引モデルが issue の本文から書いたものです。