[BUG] Mojo Debug Tooling - Debugger throws non-helpful error message with no additional information

[thatstoasty]

Bug description

Reposting from Discord: https://discord.com/channels/1087530497313357884/1151418340548542484/1358099788465180722

Actual behavior

I'm trying to debug some code in VSCode and the debugger just returns a message thats not covered in the debugger documentation.

mojo: error: RPC Server response: Error: Unable to start the debug session

I dug in to the logs and its pretty standard, when it sends the debug request to the RPC server it just receives this response and there's nothing more:

[port=12355] Got response: {"success":false,"message":"Error: Unable to start the debug session","kind":"debug"}

I can add the request payload if needed.

Expected behavior

Steps to reproduce

• Provide a relevant code snippet or a link to the code that did not work as expected.
• If applicable, add screenshots to help explain the problem.
• If using the Playground, name the pre-existing notebook that failed and the steps that led to failure.
• Include anything else that might help us debug the issue.

System information

• Provide the system information by running magic info.

     Magic version: 0.6.4
System
------------
       Pixi version: 0.40.3
           Platform: osx-arm64
   Virtual packages: __unix=0=0
                   : __osx=15.3.2=0
                   : __archspec=1=m2
          Cache dir: /Users/mikhailtavarez/Library/Caches/rattler/cache
       Auth storage: /Users/mikhailtavarez/.rattler/credentials.json
   Config locations: No config files found

• Provide version information for MAX (includes Mojo) by pasting the output of magic list max.

Package     Version  Build    Size       Kind   Source
max         25.2.0   release  9.6 KiB    conda  max
max-core    25.2.0   release  220.4 MiB  conda  max-core
max-python  25.2.0   release  111.1 MiB  conda  max-python