WIP Correlate sent errors with received errors.

[erights]

This is a delta to the hackathon branch as a temporary approximation of a future change.

When sending errors over marshal, generate an errorId to uniquely identify this error sending and use assert.note to associate that errorId with both the error as sent and the copy of that error as received. Somehow remember the association of that errorId with the sent error so that the sent error's hidden debug information --- details and stack trace --- can be correlated with the received error, should the received error be reported.

As a temporary stopgap for the hackathon, this PR takes the following shortcuts:

• Rather than use some internal log or bookkeeping mechanism to associate the errorId with the sent error, just log the sent error to the console, so the association gets printed to the log. This is adequate but painful for human eyeballs for find the association. It is not suitable for a Causeway-like automated tool to stitch together the distributed causality graph.
• The errorId is not very unique. We're currently only using increasing counts relative to a marshal instance.

This is currently a WIP Draft because it does not yet have new tests for this functionality.

[michaelfig]

LGTM, glad that tests pass. 💯

[katelynsills]

the changes look good to me, but I would need to see how they affect what the user sees.

[Chris-Hibbert]

This seems good. How hard would it be to add a command-line flag to turn this reporting on or off? If it's as verbose as you imply, it would be nice to only get it when someone is tracking a problem down. (Though how many of our developers would know where to turn on the flag?)

[michaelfig]

This seems good. How hard would it be to add a command-line flag to turn this reporting on or off?

https://github.com/Agoric/agoric-sdk/pull/2037/files#r526533669

[erights]

I report progress at Agoric/dapp-fungible-faucet#10 (comment)

Without the -v flag the experience is unchanged. With it, the experience is miserably verbose and unclear. But it does contain the needed clues, so is arguably better than the status quo.

[katelynsills]

Merging as per discussion in this morning's meeting.