Debugging tools that can be used with Unity in Native OS and multithreading envi?

When you code using Native OS(Win,Osx) API (unsafe) even Null object reference can crash Unity, and try catch blocks are useless same as logs containing registry data. Problem become even harder cos most of OS API's are multithreading and hard to track bugs happen in communication to Unity single thread play mode and worst in editor mode. Please share some tools you are using beside stacktrace and nunit where can I see thread execution visually or/and data...I feel tools haven't got far from text editor for 20years. Maybe some plugins for VS or something.