Make sure thrown exceptions are caught within VSCode extension (and not silently consumed)

[mmarchetti]

We have approximately 22 instances of code which throws an Error, to indicate that a logic assumption has been violated.

Recent debugging has shown that VSCode may be silently handling these without drawing attention to their occurrence, which in the recent session, cost a significant amount of time to debug.

We can do better. :-)

I searched on throw new Error to count the occurrances.