[SQD-Trevor-Agent]

Cause (proven)

dump-cronos-mainnet-traceless-0 (evm-archive namespace) was in CrashLoopBackOff (17+ restarts). The fatal error, from the pod's previous-container logs, is a non-retryable AssertionError in Rpc.mapBlock:

AssertionError [ERR_ASSERTION]: The expression evaluated to a falsy value:
  (val != null, msg)
    at assertNotNull (/squid/util/util-internal/lib/misc.js:52:26)
    at Rpc.mapBlock (/squid/evm/evm-rpc/lib/rpc.js:177:65)   // = assertNotNull(block.withdrawals)
  { blockNumber: 101503527, blockHash: 0x9a64993c364da9321a4801c74a188e31e042e95d15105817a76b1a7f0fb692c8 }

Cronos runs with --verify-withdrawals-root. In mapBlock, when block.withdrawalsRoot != null the code did assertNotNull(block.withdrawals). Cronos (a Cosmos-EVM chain) has no withdrawals: its header withdrawalsRoot is the canonical empty-trie root 0x56e81f17…b421 and the block body carries withdrawals: []. Fetched directly, both independent providers (dwellir and uniblock) return withdrawals: [] with that empty root — the on-chain data is well-formed. But the response occasionally arrives with the empty withdrawals array omitted (undefined), and assertNotNull then turns that transient omission into a process crash — a crash-loop, since the dumper re-reaches the same block on every restart.

This was confirmed as transient, not corrupt data: after the eRPC cache for block 101503527 was re-warmed, the dumper processed it cleanly and advanced past it (restart count held steady) — i.e. the field was present again.

Fix

Treat an omitted withdrawals array as [] (block.withdrawals ?? []). The subsequent assert.equal(block.withdrawalsRoot, computedRoot) still guards correctness: an empty list computes to the empty root (so Cronos verifies), while a genuinely missing non-empty set computes to the empty root and fails verification instead of being silently accepted.

Test (red→green)

test/rpc.test.ts:

• tolerates an omitted empty withdrawals array — a block with the empty withdrawalsRoot and no withdrawals field verifies and returns 1 block.

• still rejects a missing non-empty withdrawals set — a block with a non-empty withdrawalsRoot and no withdrawals field throws failed to verify withdrawals root.

• pre-fix: Tests 2 failed (both throw the assertNotNull falsy-value AssertionError)

• post-fix: Tests 2 passed

• full @subsquid/evm-rpc suite green (rush build -t @subsquid/evm-rpc clean; tsc --noEmit -p tsconfig.test.json clean). One unrelated base-mainnet sender-recovery test hits the 5 s default timeout on slow hardware and passes at --testTimeout=60000.

Falsification

If dump-cronos-mainnet-traceless-0 still exits with this assertNotNull AssertionError after this change, the omission is not what crashes it. If it instead starts failing failed to verify withdrawals root, a provider is returning a non-empty withdrawalsRoot without the matching withdrawals — a genuine provider data-quality issue to raise upstream.

Related to #551 (same crash-loop class — a transient provider/proxy response killing the dumper) but a distinct path: #551 converts schema-validation errors to retries; this block passes schema validation (withdrawals is optional) and crashes later in mapBlock.