Engine: Print Debug Traceback on Graph Interpretation Error

[joeltio]

The evaluation of the computation graph on the engine is done through a recursive function. The function does not have sufficient error handling to pinpoint the exact node which caused the error. This makes debugging graphs difficult.

Currently, the only way to debug the graphs is through a debugger, stepping through each node manually.

[joeltio]

C++11 has introduced nested exceptions, allowing us to create our own traceback. This is likely what will be used to implement this. See https://en.cppreference.com/w/cpp/error/nested_exception