fix(portal): actionable error when a dataset lacks a requested table

[abernatskiy]

Summary

• A trace/transfer source on a dataset with no traces table — a network that omits call traces entirely (e.g. celo), or one that only serves them above a cutoff block (e.g. optimism below the Bedrock block) — surfaced the raw Portal 400 couldn't parse request: table 'traces' does not exist, with no hint about the cause or the fix.
• The missing-column path already degrades / fails loud with a precise message (parseSchemaFieldError); the missing-table case fell through to a generic PortalHttpError. This adds a typed PortalMissingTableError and rewords it in the stream loop (mirroring the PortalQueryTooLargeError lever) into a message naming the chain, the unavailable source, and the remedy.
• Consistent with the fork's established "enrich the actionable message" approach for errors that can surface via the prefetch fan-out (cf. PortalThrottleExhaustedError, Portal throttle (429) on a full backfill against the free public Portal exhausts retries and crashes via unhandledRejection — should degrade/backoff or fail with an actionable error #116) — it does not change async error propagation.

Example before → after (optimism call traces below Bedrock):

PortalHttpError: Portal 400 @ 105000000: Bad request: couldn't parse request: table 'traces' does not exist

Portal dataset for optimism does not serve call traces over blocks [105000000,105000010]. Some networks omit it entirely; others only serve it above a cutoff block (e.g. Optimism call traces from the Bedrock block). remove the trace sources (contract \includeCallTraces`, and `account`/`transfer` filters) for this chain, or index a network/range that provides it.`

Coverage (Portal layer)

File	Stmts	Δ	Branch	Δ	Funcs	Δ
All files	98.4%	±0	89.7%	±0	98.5%	±0

New code fully covered (specific traces message + generic fallback); overall coverage unchanged.

Test plan

• scripts/sync-upstream.sh 0.16.9 --coverage green — 330 passed (18 files); adds 2 tests in portal-client.test.ts (specific traces message + generic fallback)
• biome check . clean
• Covered: the table '<t>' does not exist 400 maps to PortalMissingTableError and reworsds into an actionable, source-named message; a table with no specific entry falls back to a generic named message; an unrelated 400 still surfaces as PortalHttpError (unchanged).

🤖 Generated with Claude Code