Bug: Fix error formatting

[0xThiebaut]

What does this PR do?

Fix error formatting.

Why is it important?

To avoid funky error reporting such as:

2025-03-12T16:38:11.740Z ERROR [metrics] map[file.line:40 file.name:report/metrics_file_descriptors.go function:github.com/elastic/elastic-agent-system-metrics/report.SetupLinuxBSDFDMetrics.FDUsageReporter.func1] Error while retrieving FD information: %verror fetching PID 38644: GetInfoForPid: no such process {"ecs.version": "1.6.0"}

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.md

Author's Checklist

• [ ]

Related issues

[cla-checker-service]

💚 CLA has been signed

[0xThiebaut]

Signed the CLA.

[mauri870]

LGTM! I left some minor feedback. Thanks for your contribution!

[0xThiebaut]

Thanks for the review! I went ahead and applied your suggested change in a couple more places.

[mauri870]

Thanks!

[belimawr]

It looks great, thanks for the contribution!

There is just one %v you missed.

[0xThiebaut]

Added another couple more. Looking for %v in the code base highlights quite some other locations that might benefit from a quick refactor but this goes beyond the error formatting I was focusing on.

[0xThiebaut]

I'll review the failed linting, seems one Errorf is not known.

[belimawr]

buildkite test this

[belimawr]

The failing test seems unrelated, I created a flaky test issue: #212

[belimawr]

buildkite test this

[0xThiebaut]

@belimawr As the buildkite results are not public, can you let me know if the failures are caused by the PR?

For the linting errors, I don't believe these are caused by this PR.

[belimawr]

@belimawr As the buildkite results are not public, can you let me know if the failures are caused by the PR?

For the linting errors, I don't believe these are caused by this PR.

TestContainerProcess/nsmode:private_priv:false_user is failing on CI. I've run the tests on my machine and they're passing.

The failure does not look related to the PR.

Today or tomorrow I'll take a deeper look at it.

[belimawr]

This flaky test is very OS dependant, on CI it is failing on Rhel 9, we'll get someone that knows this test better to take a look at it.