Code color(not colored) sets to editor.foreground instead of #000000

[huacat1017]

Steps to reproduce:

1. Install C/C++ Themes and use the theme
2. Install Markdown Preview VS Code Highlighting
3. Create a new Markdown file and type these:

```bash
sh build.sh p3
```
```cpp
#include <iostream>
using namespace std;
int main(){
    cout << "Hello World";
}
```

4. Can't see some texts because the color is #000000

I studied about this months ago. In my opinion, if the theme developers don't specify this below in their json theme file:

"tokenColors":[
  {
    "name": "Global settings",
    "settings": {
      "foreground": "#ffffff" // If they specify it with editor.foreground hex code, the black texts will change back to the properly color that matches the bg color.
    }
  }
]

, the texts that they don't color through the TextMate's Scopes will stay #000000 even if it is a dark theme. And it's almost unable for me to read.
You can see more clearly through this picture: (Theme: Github Dark in Github Theme)

I wonder if there's a way to replace the foreground in TextMate token colors with editor.foreground the theme developer specified when the program reads the json file of the theme. I'm bad at JS/TS, so I would ask you if you can fix this.
Thank you for reading this!