Remove anyhow from re_ros_msg and re_arrow_util

[emadak47]

Related

• Part of Replace anyhow with thiserror in libraries #1845

What

• removed anyhow from public fns in utils/ crates

[grtlr]

Thank you for your PR! The motivation behind

• #1845

is to have more structured error reporting that can replace the functionality provided by anyhow while allowing downstream processing. Yet this PR does not add any structure beyond the single variant ArrayComparisonError.

For example, I would expect an Error::ChildCountMismatch (or similar) variant in re_arrow_util. The ROS-related errors go into the right direction.

[emadak47]

thank you for the feedback.

originally, I focused on current usage; since no callers match on variants, I went for a simple unit struct ArrayComparisonError. But that's not better than anyhow::Error, it's a string with a different hat.

I've added as many error variants as I deemed necessary, reducing further would lose meaningful distinctions, but I'm happy to hear your opinion if you disagree.