handle an edge case in newpayload block execution (#3131)

* handle an edge case in newpayload block execution

* comment cleanup

---------

Co-authored-by: Holger Drewes <Holger.Drewes@gmail.com>

packages/client/src/rpc/modules/engine.ts

@@ -924,20 +924,35 @@ export class Engine {
         }
       }
     } catch (error) {
+      const latestValidHash = await validHash(
+        headBlock.header.parentHash,
+        this.chain,
+        this.chainCache
+      )
+
       const errorMsg = `${error}`.toLowerCase()
       if (errorMsg.includes('block') && errorMsg.includes('not found')) {
-        throw {
-          code: INTERNAL_ERROR,
-          message: errorMsg,
+        if (blocks.length > 1) {
+          // this error can come if the block tries to load a previous block yet not in the chain via BLOCKHASH
+          // opcode.
+          //
+          // i)  error coding of the evm errors should be a better way to handle this OR
+          // ii) figure out a way to pass let the evm access the above blocks which is what connects this
+          //     chain to vmhead. to be handled in skeleton refactoring to blockchain class
+
+          const response = { status: Status.SYNCING, latestValidHash, validationError: null }
+          return response
+        } else {
+          throw {
+            code: INTERNAL_ERROR,
+            message: errorMsg,
+          }
         }
       }
+
       const validationError = `Error verifying block while running: ${errorMsg}`
       this.config.logger.error(validationError)
-      const latestValidHash = await validHash(
-        headBlock.header.parentHash,
-        this.chain,
-        this.chainCache
-      )
+
       const response = { status: Status.INVALID, latestValidHash, validationError }
       this.invalidBlocks.set(blockHash.slice(2), error as Error)
       this.remoteBlocks.delete(blockHash.slice(2))