Fix case where some Exceptions have no traceback. (#14153)...
Fix case where some Exceptions have no traceback. (#14153)
In chained exception if some exceptions does not have tracebacks,
prevent jumping to them.
We also add the assert that the main exception does have a traceback.
This is a partial port of python/cpython commit
5f3433f210d25d366fcebfb40adf444c8f46cd59
