v2.0: Improves panic message if send() fails in streaming_unpack_snapshot() (backport of #2459)

[mergify]

Problem

There are reports on Discord¹² of people hitting panics while sending on a channel during snapshot unpacking. Here's an example:

thread 'solUnpkSnpsht01' panicked at /var/lib/buildkite-agent/builds/release/anza/agave-secondary/accounts-db/src/hardened_unpack.rs:338:45:
called `Result::unwrap()` on an `Err` value: "SendError(..)"
stack backtrace:

The unwrap doesn't yield the best panic message...

Summary of Changes

Improve the panic message.

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This is an automatic backport of pull request #2459 done by Mergify.

Backport Reasoning

I'd like to backport this so we have a better panic message. Maybe this help elucidate why some people have been hitting this panic. Minimally I'd like to have the path information the new message provides.

If we do not backport, we'd have to wait until v2.1 before we could get any additional information.

This backport does not change any behavior, just expands the logging.

Footnotes

1. https://discord.com/channels/428295358100013066/560174212967432193/1270412894026207305 ↩

2. https://discord.com/channels/428295358100013066/837340113067049050/1270052679309328408 ↩

[steviez]

Oops, this one slipped through the cracks. We figured out why were seeing the panics, but doesn't hurt to ship this so LGTM