problem: fails to respond when requested block doesn't exist

src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/EthereumDirectReader.kt

@@ -114,9 +114,13 @@ class EthereumDirectReader(
         return readWithQuorum(request)
                 .timeout(Defaults.timeoutInternal, Mono.error(TimeoutException("Block not read $id")))
                 .retryWhen(Retry.backoff(3, Duration.ofSeconds(1)))
-                .map { blockbytes ->
+                .flatMap { blockbytes ->
-                    val block = objectMapper.readValue(blockbytes, BlockJson::class.java) as BlockJson<TransactionRefJson>
+                    val block = objectMapper.readValue(blockbytes, BlockJson::class.java) as BlockJson<TransactionRefJson>?
-                    BlockContainer.from(block, blockbytes)
+                    if (block == null) {
+                        Mono.empty<BlockContainer>()
+                    } else {
+                        Mono.just(BlockContainer.from(block, blockbytes))
+                    }
                 }
                 .doOnNext { block ->
                     caches.cache(Caches.Tag.REQUESTED, block)

src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumDirectReaderSpec.groovy

@@ -69,6 +69,34 @@ class EthereumDirectReaderSpec extends Specification {
                 .verify(Duration.ofSeconds(1))
     }
 
+    def "Produce empty result on non-existing block"() {
+        setup:
+        def up = Mock(Multistream) {
+            1 * getApiSource(_) >> Stub(ApiSource)
+        }
+        def calls = Mock(Factory) {
+            1 * create() >> new DefaultEthereumMethods(Chain.ETHEREUM)
+        }
+        EthereumDirectReader reader = new EthereumDirectReader(
+                up, Caches.default(), new CurrentBlockCache(), calls
+        )
+        reader.quorumReaderFactory = Mock(QuorumReaderFactory) {
+            1 * create(_, _) >> Mock(Reader) {
+                1 * read(new JsonRpcRequest("eth_getBlockByHash", [hash1, false])) >> Mono.just(
+                        new QuorumRpcReader.Result(
+                                Global.objectMapper.writeValueAsBytes(null), 1
+                        )
+                )
+            }
+        }
+        when:
+        def act = reader.blockReader.read(BlockHash.from(hash1))
+        then:
+        StepVerifier.create(act)
+                .expectComplete()
+                .verify(Duration.ofSeconds(1))
+    }
+
     def "Reads block by height"() {
         setup:
         def json = new BlockJson().tap {
@@ -143,6 +171,34 @@ class EthereumDirectReaderSpec extends Specification {
                 .verify(Duration.ofSeconds(1))
     }
 
+    def "Produce empty on non-existing tx"() {
+        setup:
+        def up = Mock(Multistream) {
+            1 * getApiSource(_) >> Stub(ApiSource)
+        }
+        def calls = Mock(Factory) {
+            1 * create() >> new DefaultEthereumMethods(Chain.ETHEREUM)
+        }
+        EthereumDirectReader reader = new EthereumDirectReader(
+                up, Caches.default(), new CurrentBlockCache(), calls
+        )
+        reader.quorumReaderFactory = Mock(QuorumReaderFactory) {
+            1 * create(_, _) >> Mock(Reader) {
+                1 * read(new JsonRpcRequest("eth_getTransactionByHash", [hash1])) >> Mono.just(
+                        new QuorumRpcReader.Result(
+                                Global.objectMapper.writeValueAsBytes(null), 1
+                        )
+                )
+            }
+        }
+        when:
+        def act = reader.txReader.read(TransactionId.from(hash1))
+        then:
+        StepVerifier.create(act)
+                .expectComplete()
+                .verify(Duration.ofSeconds(1))
+    }
+
     def "Reads balance - height is unknown"() {
         setup:
         def up = Mock(Multistream) {

testing/trial/src/test/groovy/io/emeraldpay/dshackle/testing/trial/proxy/StandardCallsSpec.groovy

@@ -31,6 +31,33 @@ class StandardCallsSpec extends Specification {
         act.error == null
     }
 
+    def "get non-existing block"() {
+        when:
+        def act = client.execute("eth_getBlockByNumber", ["0x200001", false])
+        then:
+        act.result == null
+        act.error == null
+    }
+
+    def "get tx"() {
+        when:
+        def act = client.execute("eth_getTransactionByHash", ["0x01c5a8461d06c2c195035c148af0f871c7679841d86ae5bb98676bb2d8e68dfa"])
+        then:
+        act.result != null
+        with(act.result) {
+            blockHash == "0x9a834c53bbee9c2665a5a84789a1d1ad73750b2d77b50de44f457f411d02e52e"
+        }
+        act.error == null
+    }
+
+    def "get non-existing tx"() {
+        when:
+        def act = client.execute("eth_getTransactionByHash", ["0x000000461d06c2c195035c148af0f871c7679841d86ae5bb98676bb2d8e68dfa"])
+        then:
+        act.result == null
+        act.error == null
+    }
+
     def "get block with txes"() {
         when:
         def act = client.execute("eth_getBlockByNumber", ["0x100001", true])