Remove strerror in favor of decode_error

[mkeeter]

(staged on #682)

This is a small PR to consolidate IpcError decoding into a single place (IdolOperation::decode_error).

I don't try to preserve the exact error formatting; if you have opinions on what information would be useful, see #680 for where the new error type is introduced. I'd be surprised if anyone was parsing CLI output for exact strings here, but cc @adamlouis just in case.

[hawkw]

nit, take it or leave it: now that this is no longer using bail, i feel like it could be changed to something like

results[rindex].map_err(|err| op.decode_error(err).context("failed to take dump")?;

also: i was...quite struck...by the potential alternative interpretation of the string "failed to take dump". if this is not immediately obvious to you, you're probably better off that way!

[mkeeter]

sooooo I considered writing it in that form, but vaguely decided against it for two reasons:

• rustfmt wraps onto multiple lines, so it's not any shorter
• Vague vibes: I feel like ? as a way to return an error – when you're not using the actual value – is a little less obvious than an explicit return. It's fine in a chain where the end result is used, but seems to sneaky when used as a one-character conditional return.

(I have no further comment on the text of the string 🙈)

[hawkw]

take it or leave it: this could ? now that it no longer uses bail!?

[mkeeter]

Same here, I'd rather be explicit versus result.map_err(...)?

[Copilot]

Pull request overview

Consolidates Idol IPC error decoding by removing IdolOperation::strerror and routing callers through the typed IdolOperation::decode_error path, so Idol error interpretation lives in one place.

Changes:

• Removed IdolOperation::strerror from humility-idol in favor of IdolOperation::decode_error.
• Updated humility-dump-agent to surface decoded Idol errors via anyhow::Context chains.
• Updated cmd/pmbus to format errors via decode_error(...).to_string().

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
humility-idol/src/lib.rs	Removes strerror API to centralize error decoding in decode_error.
humility-dump-agent/src/hiffy.rs	Replaces strerror usage with typed decode + contextual error propagation.
cmd/pmbus/src/lib.rs	Switches error-to-string formatting from strerror to decode_error.

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