test(core): cover error/validation branches in ar/pattern.rs + kpm/freak/pyramid.rs (5 lines)

[kalwalt]

Summary

Codecov flagged 5 uncovered lines on the v0.8.0 release PR (#223) — patch coverage 97.98%. These are pre-existing gaps surfaced by the release diff, not a regression. Tracking them here as a post-release test follow-up.

File	Patch %	Missing
crates/core/src/ar/pattern.rs	70.00%	3 lines
crates/core/src/kpm/freak/pyramid.rs	88.89%	2 lines

Exact lines: see the Codecov report for #223.

Likely culprits (error/validation branches)

These files are dominated by arlog_e! + return Err(...) guard clauses that no test exercises:

• ar/pattern.rs — activate/deactivate/index guards, e.g.:

  • ar_patt_activate: "Invalid pattern index" / "Pattern not loaded" (pattern.rs:275-302)
  • ar_patt_load_from_buffer: parse-failure / unexpected-EOF paths (pattern.rs:113-118)

• kpm/freak/pyramid.rs — Pyramid::build validation, e.g.:

  • ZeroLevels / InvalidScaleFactor / EmptyImage / LevelTooSmall (pyramid.rs:150-185)

  Note: pyramid.rs is the box-filter Pyramid kept as a reference but not wired into the live pipeline (chore(kpm): decide fate of unused BoxFilterPyramid8u (wire in or remove) #203), so its branches are naturally under-exercised.

Suggested fix

Add small unit tests asserting the Err variants for each guard (cheap, deterministic, no image pipeline needed) — mirrors the edge-case tests added for M9 coverage in #177. Target: bring both files' patch coverage to 100% and nudge the ar + kpm::freak module totals up.

Related

• Surfaced on Release v0.8.0 (dev → main) #223 (v0.8.0 release)
• Pattern follows test(kpm): raise patch coverage on M9 modules (84.76% → target ≥90%) #177 (raise M9 coverage with edge-case tests)
• chore(kpm): decide fate of unused BoxFilterPyramid8u (wire in or remove) #203 (box-filter Pyramid kept-but-unused)