🐞 Opening a folder with source files only shows empty files in the editor

### Description

When I click ***Open file or folder*** and select a folder containing *.h and *.cpp source files, the file tree is correctly displayed. But when I try to open a source file in the editor, it only shows an empty file.
However when I open a standard text file which is also contained in the folder, the file contents show normally.

### To Reproduce

1. Click **_Open file or folder_**
2. Open a folder containing *.h and *.cpp files
3. Open a file in the editor

### Expected Behavior

The editor should show the file contents.

### Version Information

CodeEdit: Current GitHub clone (Commit #1718)
macOS: 14.5.1
Xcode: 15.4

### Additional Context

_No response_

### Screenshots

首先，在 macOS 上准备一个包含 .h 和 .cpp 文件的文件夹，通过“Open file or folder”入口复现该问题。跟踪文件夹打开和编辑器加载的路径，然后验证打开这些源文件时会显示其内容，同时标准文本文件仍能正常工作。

由索引模型根据 Issue 内容生成。