Can't get into debugger in vscode on macOS

[Daniel Zuncke]

Hello, I need some help getting into the debugger in vscode on 
macOS. It did work some months ago but that was finicky to set 
up. Maybe I am forgetting something now?

I am compiling the project with `dub build --build debug 
--compiler ldc2 --force` (the `-ld_classic` flag to fix the new 
Xcode linker is set in dub.json).

Debugging in the terminal with lldb works as expected `lldb 
bin/dfmt -- --help`.

In vscode I the debug process immediately exits with error (as 
far as I can tell, don't know how to get more output).
All required extensions should be installed since it worked some 
time ago (mainly CodeLLDB, code-d and C++ from what I remember).

I have tried 2 launch configs (launch.json):
```json
{
     "version": "0.2.0",
     "configurations": [
         {
             "type": "lldb",
             "request": "launch",
             "name": "debug lldb",
             "cwd": "${workspaceFolder}",
             "program": "./bin/dfmt",
             "args": ["--help"],
         },
         {
             "type": "code-d",
             "request": "launch",
             "name": "debug code-d",
             "cwd": "${workspaceFolder}",
             "program": "./bin/dfmt",
             "args": ["--help"],
         },
     ]
}
```
And both fail the same way (vscode Debug Console output):
```
Launching: /Users/dz/dev/dfmt/issue578/bin/dfmt --help
Launched process 24999
Process exited with code -1.
```
Any ideas what the problem could be? Can I get more verbose 
output what the problem is after launching the process?