More verbose error log (#2864)

abci/client/grpc_client.go

@@ -54,7 +54,7 @@ RETRY_LOOP:
 			if cli.mustConnect {
 				return err
 			}
-			cli.Logger.Error(fmt.Sprintf("abci.grpcClient failed to connect to %v.  Retrying...\n", cli.addr))
+			cli.Logger.Error(fmt.Sprintf("abci.grpcClient failed to connect to %v.  Retrying...\n", cli.addr), "err", err)
 			time.Sleep(time.Second * dialRetryIntervalSeconds)
 			continue RETRY_LOOP
 		}

abci/client/socket_client.go

@@ -67,7 +67,7 @@ RETRY_LOOP:
 			if cli.mustConnect {
 				return err
 			}
-			cli.Logger.Error(fmt.Sprintf("abci.socketClient failed to connect to %v.  Retrying...", cli.addr))
+			cli.Logger.Error(fmt.Sprintf("abci.socketClient failed to connect to %v.  Retrying...", cli.addr), "err", err)
 			time.Sleep(time.Second * dialRetryIntervalSeconds)
 			continue RETRY_LOOP
 		}