[FIX] Fix NPE thrown during cake building (#813)

Author: kapke

src/main/scala/io/iohk/ethereum/consensus/ConsensusBuilder.scala

@@ -55,6 +55,7 @@ trait StdConsensusBuilder extends ConsensusBuilder {
       config.protocol match {
         case Protocol.Ethash | Protocol.MockedPow | Protocol.RestrictedEthash => buildEthashConsensus()
       }
+
     log.info(s"Using '${protocol.name}' consensus [${consensus.getClass.getName}]")
 
     consensus

src/main/scala/io/iohk/ethereum/nodebuilder/NodeBuilder.scala

@@ -285,7 +285,7 @@ trait TransactionHistoryServiceBuilder {
 object TransactionHistoryServiceBuilder {
   trait Default extends TransactionHistoryServiceBuilder {
     self: BlockchainBuilder with PendingTransactionsManagerBuilder with TxPoolConfigBuilder =>
-    val transactionHistoryService =
+    lazy val transactionHistoryService =
       new TransactionHistoryService(blockchain, pendingTransactionsManager, txPoolConfig.getTransactionFromPoolTimeout)
   }
 }
@@ -351,7 +351,7 @@ trait EthServiceBuilder {
     with JSONRpcConfigBuilder
     with AsyncConfigBuilder =>
 
-  val ethService = new EthService(
+  lazy val ethService = new EthService(
     blockchain,
     ledger,
     stxLedger,

src/test/scala/io/iohk/ethereum/jsonrpc/MantisServiceSpec.scala

@@ -67,7 +67,7 @@ class MantisServiceSpec
           )
         )
 
-        override val transactionHistoryService: TransactionHistoryService =
+        override lazy val transactionHistoryService: TransactionHistoryService =
           new TransactionHistoryService(
             blockchain,
             pendingTransactionsManager,