A block the engine builds itself that fails its own Verify() was dropped with a bare
continue — no log at any level. Because the VM re-notifies while its txs remain in the
mempool, the engine rebuilds and re-drops indefinitely: an invisible hot loop (observed
4.07M consecutive 'built block' lines with the chain stuck at height 1 and zero errors
logged). Dropping an unverifiable block is correct; doing it silently is not.
zeekay
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