problem: looses upstream error details

src/main/kotlin/io/emeraldpay/dshackle/rpc/NativeCall.kt

@@ -284,11 +284,7 @@ open class NativeCall(
                 Mono.just(ctx).flatMap(this::executeOnRemote)
             )
             .onErrorResume {
-                if (it is CallFailure) {
-                    Mono.just(CallResult.fail(it.id, ctx.nonce, it.reason))
-                } else {
-                    Mono.just(CallResult.fail(ctx.id, ctx.nonce, it))
-                }
+                Mono.just(CallResult.fail(ctx.id, ctx.nonce, it))
             }
     }
 
@@ -310,21 +306,14 @@ open class NativeCall(
                 CallResult(ctx.id, ctx.nonce, bytes, null, it.signature, ctx.upstream.getId())
             }
             .onErrorResume { t ->
-                val failure = when (t) {
-                    is CallFailure -> CallResult.fail(t.id, ctx.nonce, t.reason)
-                    is JsonRpcException -> CallResult.fail(ctx.id, ctx.nonce, t.error.code, t.error.message)
-                    else -> CallResult.fail(ctx.id, ctx.nonce, t)
-                }
-                Mono.just(failure)
+                Mono.just(CallResult.fail(ctx.id, ctx.nonce, t))
             }
             .switchIfEmpty(
                 Mono.fromSupplier {
                     counter.get().let { attempts ->
                         CallResult.fail(
-                            ctx.id,
-                            ctx.nonce,
-                            1,
-                            errorMessage(attempts, ctx.payload.method)
+                            ctx.id, ctx.nonce,
+                            CallError(1, "No response or no available upstream for ${ctx.payload.method}", null)
                         ).also {
                             countFailure(attempts, ctx)
                         }
@@ -484,7 +473,15 @@ open class NativeCall(
                     is JsonRpcException -> CallError(t.id.asNumber().toInt(), t.error.message, t.error)
                     is RpcException -> CallError(t.code, t.rpcMessage, null)
                     is CallFailure -> CallError(t.id, t.reason.message ?: "Upstream Error", null)
-                    else -> CallError(1, t.message ?: "Upstream Error", null)
+                    else -> {
+                        // May only happen if it's an unhandled exception.
+                        // In this case try to find a meaningless details in the stack. Most important reason for doing that is to find an ID of the request
+                        if (t.cause != null) {
+                            from(t.cause!!)
+                        } else {
+                            CallError(1, t.message ?: "Upstream Error", null)
+                        }
+                    }
                 }
             }
         }
@@ -503,8 +500,8 @@ open class NativeCall(
                 return CallResult(id, nonce, result, null, signature, upstreamId)
             }
 
-            fun fail(id: Int, nonce: Long?, errorCore: Int, errorMessage: String): CallResult {
-                return CallResult(id, nonce, null, CallError(errorCore, errorMessage, null), null, null)
+            fun fail(id: Int, nonce: Long?, error: CallError): CallResult {
+                return CallResult(id, nonce, null, error, null, null)
             }
 
             fun fail(id: Int, nonce: Long?, error: Throwable): CallResult {

src/test/groovy/io/emeraldpay/dshackle/rpc/NativeCallSpec.groovy

@@ -34,6 +34,8 @@ import io.emeraldpay.dshackle.upstream.Selector
 import io.emeraldpay.dshackle.upstream.MultistreamHolder
 import io.emeraldpay.dshackle.upstream.calls.DefaultEthereumMethods
 import io.emeraldpay.dshackle.upstream.calls.ManagedCallMethods
+import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcError
+import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcException
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcResponse
 import io.emeraldpay.dshackle.upstream.signature.ResponseSigner
@@ -156,6 +158,35 @@ class NativeCallSpec extends Specification {
                 .verify(Duration.ofSeconds(1))
     }
 
+    def "Returns error details from remote"() {
+        setup:
+        def quorum = new AlwaysQuorum()
+
+        def nativeCall = nativeCall()
+        nativeCall.quorumReaderFactory = Mock(QuorumReaderFactory) {
+            1 * create(_, _, _) >> Mock(Reader) {
+                1 * read(new JsonRpcRequest("eth_test", [], 10)) >> Mono.error(
+                        new JsonRpcException(JsonRpcResponse.Id.from(12), new JsonRpcError(-32123, "Foo Bar", "Foo Bar Baz"))
+                )
+            }
+        }
+        def call = new NativeCall.ValidCallContext(12, 10, TestingCommons.multistream(TestingCommons.api()), Selector.empty, quorum,
+                new NativeCall.ParsedCallDetails("eth_test", []))
+
+        when:
+        def resp = nativeCall.executeOnRemote(call).block(Duration.ofSeconds(1))
+        then:
+        resp.isError()
+        with(resp.getError()) {
+            message == "Foo Bar"
+            upstreamError != null
+            with (upstreamError) {
+                code == -32123
+                details == "Foo Bar Baz"
+            }
+        }
+    }
+
     def "Packs call exception into response with id"() {
         setup:
         def nativeCall = nativeCall()