🐞 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

Start by reproducing the issue through the “Open file or folder” entry point with a folder containing .h and .cpp files on macOS. Trace the folder-opening and editor-loading path, then verify that opening those source files displays their contents while standard text files continue to work.

Written by the indexing model from the issue text.