[ETCM-927] improve error messages in EthBlockService.getBlockByHash()

Author: strauss-m

src/main/scala/io/iohk/ethereum/testmode/TestEthBlockServiceWrapper.scala

@@ -33,10 +33,11 @@ class TestEthBlockServiceWrapper(
     .getByBlockHash(request)
     .map(
       _.map(blockByBlockResponse => {
+        import io.iohk.ethereum.utils.ByteStringUtils._
         blockByBlockResponse.blockResponse
-          .toRight("missing block response")
+          .toRight(s"EthBlockService: unable to find block for hash ${request.blockHash.toHex}")
           .flatMap(baseBlockResponse => baseBlockResponse.hash.toRight(s"missing hash for block $baseBlockResponse"))
-          .flatMap(hash => ledger.getBlockByHash(hash).toRight(s"unable to find block for hash=$hash"))
+          .flatMap(hash => ledger.getBlockByHash(hash).toRight(s"Ledger: unable to find block for hash=${hash.toHex}"))
           .map(fullBlock =>
             BlockByBlockHashResponse(
               blockByBlockResponse.blockResponse.map(response => toEthResponse(fullBlock, response))