Implement "Synchronously check all transactions to have non-zero length"

beacon_node/execution_layer/src/engine_api/new_payload_request.rs

@@ -121,6 +121,11 @@ impl<'block, E: EthSpec> NewPayloadRequest<'block, E> {
 
         let _timer = metrics::start_timer(&metrics::EXECUTION_LAYER_VERIFY_BLOCK_HASH);
 
+        // Check that no transactions in the payload are zero length
+        if payload.transactions().iter().any(|slice| slice.is_empty()) {
+            return Err(Error::ZeroLengthTransaction);
+        }
+
         let (header_hash, rlp_transactions_root) = calculate_execution_block_hash(
             payload,
             parent_beacon_block_root,

beacon_node/execution_layer/src/lib.rs

@@ -149,6 +149,7 @@ pub enum Error {
         payload: ExecutionBlockHash,
         transactions_root: Hash256,
     },
+    ZeroLengthTransaction,
     PayloadBodiesByRangeNotSupported,
     InvalidJWTSecret(String),
     InvalidForkForPayload,

consensus/fork_choice/tests/tests.rs

@@ -1226,7 +1226,7 @@ async fn progressive_balances_cache_attester_slashing() {
         .apply_blocks_while(|_, state| state.finalized_checkpoint().epoch == 0)
         .await
         .unwrap()
-        // TODO(electra) The shuffling calculations changed between Altair and Electra. Without 
+        // TODO(electra) The shuffling calculations changed between Altair and Electra. Without
         // skipping slots this test breaks. For some reason `fork_name_unchecked` returns Altair
         // initially, even though this test harness should be initialized with the most recent fork, i.e. Electra
         .skip_slots(32)