[CORDA-2522] Improve error reporting around failed flows (#5000)

* Improve error reporting around failed flows

* Fix an index to start from 1 when printed

* Address first set of review comments

core/src/main/kotlin/net/corda/core/contracts/TransactionVerificationException.kt

@@ -292,7 +292,7 @@ abstract class TransactionVerificationException(val txId: SecureHash, message: S
     class UntrustedAttachmentsException(val txId: SecureHash, val ids: List<SecureHash>) :
             CordaException("Attempting to load untrusted transaction attachments: $ids. " +
                     "At this time these are not loadable because the DJVM sandbox has not yet been integrated. " +
-                    "You will need to install that app version yourself, to whitelist it for use. " +
+                    "You will need to manually install the CorDapp to whitelist it for use. " +
                     "Please follow the operational steps outlined in https://docs.corda.net/cordapp-build-systems.html#cordapp-contract-attachments to learn more and continue.")
 
     /*

core/src/main/kotlin/net/corda/core/serialization/internal/AttachmentsClassLoader.kt

@@ -125,8 +125,12 @@ class AttachmentsClassLoader(attachments: List<Attachment>,
                 }
                 .map(Attachment::id)
 
-        if (untrusted.isNotEmpty())
+        if (untrusted.isNotEmpty()) {
+            log.warn("Cannot verify transaction $sampleTxId as the following attachment IDs are untrusted: $untrusted." +
+                    "You will need to manually install the CorDapp to whitelist it for use. " +
+                    "Please follow the operational steps outlined in https://docs.corda.net/cordapp-build-systems.html#cordapp-contract-attachments to learn more and continue.")
             throw TransactionVerificationException.UntrustedAttachmentsException(sampleTxId, untrusted)
+        }
 
         // Enforce the no-overlap and package ownership rules.
         checkAttachments(attachments)

node/src/main/kotlin/net/corda/node/services/statemachine/FlowStateMachineImpl.kt

@@ -243,7 +243,7 @@ class FlowStateMachineImpl<R>(override val id: StateMachineRunId,
             if(t.isUnrecoverable()) {
                 errorAndTerminate("Caught unrecoverable error from flow. Forcibly terminating the JVM, this might leave resources open, and most likely will.", t)
             }
-            logger.info("Flow raised an error... sending it to flow hospital", t)
+            logger.info("Flow raised an error: ${t.message}. Sending it to flow hospital to be triaged.")
             Try.Failure<R>(t)
         }
         val softLocksId = if (hasSoftLockedStates) logic.runId.uuid else null

node/src/main/kotlin/net/corda/node/services/statemachine/StaffedFlowHospital.kt

@@ -160,7 +160,8 @@ class StaffedFlowHospital(private val flowMessaging: FlowMessaging, private val
         return errors
                 .asSequence()
                 .mapIndexed { index, error ->
-                    log.info("Flow ${flowFiber.id} has error [$index]", error)
+                    // Rely on the logging context to print details of the flow ID.
+                    log.warn("Error ${index + 1} of ${errors.size}:", error)
                     val diagnoses: Map<Diagnosis, List<Staff>> = staff.groupBy { it.consult(flowFiber, currentState, error, medicalHistory) }
                     // We're only interested in the highest priority diagnosis for the error
                     val (diagnosis, by) = diagnoses.entries.minBy { it.key }!!

node/src/main/kotlin/net/corda/node/services/statemachine/interceptors/DumpHistoryOnErrorInterceptor.kt

@@ -39,11 +39,12 @@ class DumpHistoryOnErrorInterceptor(val delegate: TransitionExecutor) : Transiti
             (record ?: ArrayList()).apply { add(transitionRecord) }
         }
 
-        // Just if we decide to propagate, and not if just on the way to the hospital.
+        // Just if we decide to propagate, and not if just on the way to the hospital. Only log at debug level here - the flow transition
+        // information is often unhelpful in the logs, and the actual cause of the problem will be logged elsewhere.
         if (nextState.checkpoint.errorState is ErrorState.Errored && nextState.checkpoint.errorState.propagating) {
-            log.warn("Flow ${fiber.id} errored, dumping all transitions:\n${record!!.joinToString("\n")}")
+            log.debug("Flow ${fiber.id} errored, dumping all transitions:\n${record!!.joinToString("\n")}")
             for (error in nextState.checkpoint.errorState.errors) {
-                log.warn("Flow ${fiber.id} error", error.exception)
+                log.debug("Flow ${fiber.id} error", error.exception)
             }
         }