chore(rivetkit): log inspector errors + standardize pino errorKey error

[abcxff]

Adds error logs to inpector requests + standardizes error errorKey for pino (was being used but not configured in base logger)

[railway-app]

🚅 Deployed to the rivet-pr-4986 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
kitchen-sink	❌ Build Failed (View Logs)	Web	May 11, 2026 at 3:42 am
website	😴 Sleeping (View Logs)	Web	May 7, 2026 at 5:48 am
frontend-inspector	❌ Build Failed (View Logs)	Web	May 6, 2026 at 7:43 pm
ladle	❌ Build Failed (View Logs)	Web	May 6, 2026 at 7:42 pm
frontend-cloud	❌ Build Failed (View Logs)	Web	May 6, 2026 at 7:41 pm
mcp-hub	✅ Success (View Logs)	Web	May 6, 2026 at 7:41 pm

[abcxff]

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• fix(pegboard): validate drain_grace_period < request_lifespan #4998 : 2 dependent PRs (#5010 , #5012 )
• fix(rivetkit): bind methods through createWriteThroughProxy #4987
• chore(rivetkit): log inspector errors + standardize pino errorKey error #4986 👈 (View in Graphite)
• [slop]fix(rivetkit): remove async drizzle db proxy #4984 : 2 other dependent PRs (#4985 , #4991 )
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[claude]

PR Review: chore(rivetkit): log inspector errors + standardize pino errorKey error\n\n### Overview\n\nThis PR does two well-scoped things:\n1. Adds errorKey: 'error' to the base pino logger config so Pino built-in error serializer activates when an Error object is logged under the error key.\n2. Standardizes catch variable names from err to error and log field keys from err: to error: across the codebase to match that key.\n3. Adds missing logger().error(...) calls around the three inspector request handlers in native.ts so errors are no longer silently swallowed before errorResponse().\n\nThe intent is correct and the inspector logging additions are a clear improvement.\n\n### Issues\n\n#### Bug: Variable shadowing in inline-websocket-adapter.ts (lines 164-185)\n\nThe rename from err to error introduces a shadowed binding. The original code explicitly named the inner variable handlerErr to avoid this. Catch bindings are block-scoped so the behavior is correct at runtime, but the shadowing is a readability hazard and TypeScript will warn under --noShadow / strict linting. Rename the inner catch binding back to handlerError (or keep it as handlerErr).\n\n#### Style: Log message capitalization in native.ts\n\nCLAUDE.md states log messages should be lowercase unless mentioning specific code symbols. Two of the three new log messages start with a capital E: 'Error handling inspector action request' and 'Error handling inspector request'. The third is correct: 'error replaying workflow history'. Lowercase all message strings.\n\n#### Minor: Inconsistent rename in registry/index.ts Mode B shutdown handler\n\nMode A renames catch (err) to catch (error) and uses the error shorthand. Mode B keeps catch (err) but changes the field to error: err. Rename the catch variable to error for consistency with the rest of the PR.\n\n### Positive Observations\n\n- errorKey fix is correct and necessary. Without it, Pino serializes Error objects as empty objects when logged under an arbitrary key. Configuring errorKey activates the built-in error serializer (type, message, stack) automatically.\n- sleep-db.ts simplification is good. Removing the manual instanceof Error conversion is the right call now that Pino handles Error objects properly.\n- Inspector error logging additions in native.ts are a clear improvement. Errors were previously only surfaced via errorResponse() with no server-side log.\n- Runner parity is maintained. Both engine/sdks/typescript/runner/src/mod.ts and rivetkit-typescript/packages/engine-runner/src/mod.ts are updated together as required.\n- The session.ts rename is clean and correct.\n\n### Summary\n\nThe two substantive issues are the catch-variable shadowing in handleError (a readability/correctness risk if the block grows) and the capitalized log message strings. Otherwise this is a solid housekeeping PR with a real fix (errorKey) and useful new observability.