linter: whitespace, modernize, ineffassign, wastedassign

[mzihlmann]

Bundles four small, mechanical, easy-to-review linter cleanups carved from #539 (kept together since each is trivial):

• whitespace: drop unnecessary leading/trailing blank lines in function bodies
• modernize: strings.Split range loop becomes strings.SplitSeq
• ineffassign / wastedassign: remove assignments overwritten before use (uid, gid := -1, -1, val = "", r := "" become plain var or are removed)

All behaviour-preserving and generated/derived from golangci-lint. The linters themselves are not enabled in the config here, that stays in #539.

Summary by CodeRabbit

• Bug Fixes

  • Missing environment variables referenced by secret mounts now produce a clear error instead of creating an empty secret.
  • Errors encountered while unpacking build contexts are now correctly propagated.
  • Improved handling of assertion configuration and file extraction edge cases.

• Tests

  • Corrected test control flow and variable initialization to improve reliability.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/util/assert.go	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[mzihlmann]

@coderabbitai review

[coderabbitai]

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Review finished.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 50134914-11c9-47a3-8b00-69a07c2317b7

📥 Commits

Reviewing files that changed from the base of the PR and between f8e626b and b4d2413.

📒 Files selected for processing (11)

• integration/images.go
• pkg/buildcontext/tar.go
• pkg/commands/copy.go
• pkg/commands/run.go
• pkg/commands/workdir.go
• pkg/image/remote/remote.go
• pkg/util/assert.go
• pkg/util/command_util_test.go
• pkg/util/fs_util.go
• pkg/util/fs_util_test.go
• pkg/util/transport_util_test.go

💤 Files with no reviewable changes (8)

• pkg/commands/run.go
• pkg/util/transport_util_test.go
• integration/images.go
• pkg/util/fs_util.go
• pkg/commands/workdir.go
• pkg/image/remote/remote.go
• pkg/util/command_util_test.go
• pkg/buildcontext/tar.go

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📝 Walkthrough

Walkthrough

The changes adjust secret environment validation, untar error propagation, copy identity initialization, assertion parsing, extraction setup, and several loop or test block structures.

Changes

Runtime and maintenance updates

Layer / File(s)	Summary
Command error and value handling pkg/buildcontext/tar.go, pkg/commands/run.go, pkg/commands/copy.go	Build-context untar errors are returned with the directory, unset secret environment variables now fail, and copy command identity locals use zero-value initialization.
Utility parsing and extraction updates pkg/util/assert.go, pkg/util/fs_util.go, pkg/util/fs_util_test.go	Assertion parsing uses strings.SplitSeq, whiteout guard formatting changes without logic changes, and the extraction test declares its directory variable explicitly.
Loop and test structure adjustments integration/images.go, pkg/image/remote/remote.go, pkg/commands/workdir.go, pkg/util/command_util_test.go, pkg/util/transport_util_test.go	Localized loop, workdir, and test-block boundaries were adjusted without additional observable behavior.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: 0hlov3, babs, bobdu, nejch

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description summarizes the change, but it omits required template sections like issue links, checklist items, reviewer notes, and release notes.	Add the template sections: Fixes #NNN, Submitter Checklist, Reviewer Notes, and Release Notes, or delete unused blocks if not applicable.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title matches the main change set: mechanical linter-focused cleanup across whitespace, modernization, and wasted assignments.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch lint-whitespace

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