better logging

src/main/kotlin/io/emeraldpay/dshackle/quorum/QuorumRpcReader.kt

@@ -161,7 +161,7 @@ class QuorumRpcReader(
                     is JsonRpcException -> err
                     else -> JsonRpcException(
                         JsonRpcResponse.NumberId(key.id),
-                        JsonRpcError(-32603, "Unhandled internal error: ${err.javaClass}")
+                        JsonRpcError(-32603, "Unhandled internal error: ${err.javaClass}: ${err.message}")
                     )
                 }
                 quorum.record(cleanErr, null, api)

src/main/kotlin/io/emeraldpay/dshackle/upstream/grpc/GrpcHead.kt

@@ -80,6 +80,7 @@ class GrpcHead(
             .setTypeValue(chain.id)
             .build()
         return client.subscribeHead(chainRef)
+            .doOnError { log.error("subscribeHead err: ${it.message}", it) }
             // simple retry on failure, if eventually failed then it supposed to resubscribe later from outer method
             .retryWhen(Retry.backoff(4, Duration.ofSeconds(1)))
             .onErrorContinue { err, _ ->