fix(storcli2): treat absent "System Overview" as no controllers

[g-carre]

Summary

Fixes a real-hardware failure surfaced by the storcli2 e2e harness on an ARTESCA node that has no storcli2-managed controller:

error: failed to get controllers: failed to get RAID controllers:
       failed to unmarshal system overview: key not found: System Overview

storcli2 show all omits the System Overview section when "Number of Controllers": 0. The controller getter treated the missing key as a fatal error and aborted the whole inventory, so any consumer (the e2e harness, the report generator) failed on such a host instead of reporting an empty controller list.

Fix

Handle utils.ErrKeyNotFound for the System Overview section as an empty inventory (continue), exactly as the logical-volume and physical-drive getters already do for their sections.

Captured the node's real Number of Controllers: 0 output as a regression fixture (testdata/storcli2/all_no_controllers.json) and added a no managed controllers test case asserting an empty, error-free result.

Testing

go build ./..., full go test ./..., go vet, and gofmt all pass. New test case TestStorCLI2Controllers/no_managed_controllers passes.

Note: this is distinct from the existing {"Controllers":[]} case (an empty envelope, which Decode legitimately rejects). Here the envelope is a valid success payload that simply has no System Overview section.

Issue: ARTESCA-17644

🤖 Generated with Claude Code

[claude]

LGTM — the fix correctly mirrors the existing ErrKeyNotFound-as-empty-inventory pattern already used in the logical-volume and physical-drive getters. The test fixture is captured from real hardware output, and the existing index-into-controllers[0] guard in the test is properly fixed.

Review by Claude Code

[claude]

LGTM

The fix correctly handles the missing "System Overview" section by treating utils.ErrKeyNotFound as an empty inventory (return nil, nil), matching the established pattern used by the logical-volume getter (logicalvolumegetter/storcli2.go:180) and physical-drive getter (physicaldrivegetter/storcli2.go:189). The extracted controllersFromOverview method is well-documented and keeps Controllers() readable. The new test case and real-hardware fixture adequately cover the regression, and the existing assertion guard (if tt.expectedLen > 0) prevents a panic on the empty-result path.

Review by Claude Code

[claude]

LGTM — the fix correctly mirrors the existing ErrKeyNotFound → empty-inventory pattern already used by the logical-volume and physical-drive getters. The extracted controllersFromOverview method is a clean refactor, the regression fixture matches a real storcli2 payload, and the test fix for the controllers[0] guard prevents index-out-of-range on the new zero-length case.

Review by Claude Code