Debugger stops at at end of file when "stepping into"

Describe the bug

I'm trying to debug tests in Visual Studio Code. I followed this guide: https://vitest.dev/guide/debugging.html to set up the vscode debugger and everything works fine, until I "step into" a function or method. The debugger does not stop on the correct line, but at the end of the file. I created a minimal repo to reproduce the issue: https://github.com/oliverschwendener/vitest-vscode-debugging-issue. Does anyone have an idea what could cause this issue? Did I misconfigure something?

Reproduction

https://github.com/oliverschwendener/vitest-vscode-debugging-issue

Output

[INFO 15:58:09] [v0.8.4] Vitest extension is activated because Vitest is installed or there is a Vite/Vitest config file in the workspace.
[INFO 15:58:09] [API] Running Vitest: v1.5.0 (vite.config.mts)
[INFO 15:58:09] [API] Starting Vitest process with Node.js: /Users/oliverschwendener/.nvm/versions/node/v20.12.2/bin/node
[INFO 15:58:10] [API] Vitest process 94273 created
[INFO 15:58:11] [API] Collecting tests: src/Calculator.test.ts
[INFO 15:58:11] [API] Collecting tests: src/Calculator.test.ts
[INFO 15:58:33] [DEBUG] Starting debugging on localhost:53856
[INFO 15:58:33] Running 1 file(s) with name pattern: ^\s?add should add two numbers$
[Worker] Debugger listening on ws://127.0.0.1:53856/691b403d-7e0e-4ddc-8605-5c4ff72dd9f6
For help, see: https://nodejs.org/en/docs/inspector
[Worker] Debugger attached.
[INFO 15:58:33] [DEBUG] Debugging started

Version

v0.8.4

Validations

• Check that you are using the latest version of the extension
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the linked minimal reproduction repository and the Vitest VS Code debugging guide, then reproduce the stepping behavior using the reported Vitest v1.5.0 and extension v0.8.4 output. Trace where stepping into a function maps execution to source locations. Done means the debugger stops on the correct source line rather than at the end of the file.