System update status: transient `unknown` and `error` release versions are confusing

[paudmir]

While updating dogfood yesterday, I noticed some error codes would pop every now and then to later disappear without further explanation.

The update seemed to go through fine, yet I, as a user, would be doubtful it did if I saw errors without some acknowledgement of recovery or explanation of what or how critical they are.

[david-crespo]

Here is the code producing error and unknown version strings. I thought we might already have an issue for improving this, but I can't find it.

omicron/nexus/src/app/update.rs

Lines 372 to 385 in 4e43c37

	for version in sled_versions.chain(mgs_driven_versions) {
	// Don't use `version.to_string()` here because that will report
	// specific errors; instead, flatten all errors to just "error".
	// It's fine to use `.to_string()` for the non-error variants.
	let version = match version {
	internal_views::TufRepoVersion::Unknown
	| internal_views::TufRepoVersion::InstallDataset
	| internal_views::TufRepoVersion::Version(_) => {
	version.to_string()
	}
	internal_views::TufRepoVersion::Error(_) => "error".to_string(),
	};
	*counts.entry(version).or_insert(0) += 1;
	}