bug(redis): clear keys-view error banner after successful TYPE/TTL batch

[ZhuchkaTriplesix]

Parent

Part of #463

Severity

Low

Problem

In _scanBatch, a TYPE/TTL pipeline failure sets _error, but successful later batches never clear it when metadata succeeds. After a transient pipeline error, the keys list can keep updating while the error banner stays visible.

Evidence

• lib/features/redis/redis_keys_view.dart (~104–109)
• Bugbot review dev vs main (2026-07-27)

Acceptance

• Successful typesAndTtls / batch clears _error (or only the metadata error)
• New failures still set the banner
• SCAN-only failures unchanged

Suggested fix

On successful metadata fetch: _error = null in the same setState that appends keys.

[ZhuchkaTriplesix]

Fixed in #469 (merged to dev).