Added error logging and error messaging response when errors occur

[guilhermeblanco]

Att @vojtapol

[guilhermeblanco]

This also closes the graphql-java-kickstart/graphql-spring-boot#455

With this code change, I now receive the proper error feedback on all channels:

CLI:

2020-09-08 18:16:05.812  INFO 1 --- [nio-8080-exec-4] c.e.s.r.g.s.u.UserSessionSubscription    : [UserSessionSubscription] Handling subscription trackedAuctionLaneUpdates()
2020-09-08 18:16:05.846 DEBUG 1 --- [nio-8080-exec-4] o.a.a.c.query.AxonServerQueryBus         : Subscription Query requested with subscription Id [e703b015-d48e-4474-a2e9-08f83104c8b4]
2020-09-08 18:16:06.046 DEBUG 1 --- [nio-8080-exec-4] g.k.e.subscriptions.SessionSubscriber    : Subscribe to execution result: graphql.execution.reactive.DelegatingSubscription@5fe021ce
2020-09-08 18:16:06.365 ERROR 1 --- [ault-executor-1] c.e.s.r.g.s.u.UserSessionSubscription    : The mapper returned a null value.
2020-09-08 18:16:06.382 ERROR 1 --- [ault-executor-1] g.k.e.subscriptions.SessionSubscriber    : Subscription error

java.lang.NullPointerException: The mapper returned a null value.
	at java.base/java.util.Objects.requireNonNull(Objects.java:246) ~[na:na]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ UserSessionSubscription
Stack trace:
		at java.base/java.util.Objects.requireNonNull(Objects.java:246) ~[na:na]
		at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:100) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:73) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:114) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.FluxFilter$FilterSubscriber.onNext(FluxFilter.java:107) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.FluxMap$MapConditionalSubscriber.onNext(FluxMap.java:213) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:73) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1755) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at reactor.core.publisher.MonoCompletionStage.lambda$subscribe$0(MonoCompletionStage.java:86) ~[reactor-core-3.3.5.RELEASE.jar!/:3.3.5.RELEASE]
		at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073) ~[na:na]

Notice the error seems duplicate, but in reality, this block in my code is now working as intended:

        return subscriptionQueryResult.initialResult()
            .concatWith(subscriptionQueryResult.updates())
            .doOnError((e) -> log.error(e.getMessage()))
            .checkpoint("UserSessionSubscription");

Also, on GraphQL response:

{"type":"error","id":"1","payload":{"errors":[{"message":"The mapper returned a null value.","extensions":null,"path":null}]}}

[guilhermeblanco]

Last commit now fixes 2 problems:

1- Any Json related problem on decoding the incoming message would mean a crash on ApolloSubscriptionConsumer. The reason was because error was using one variable interpolation slot, but was sending two.

2- Whenever the connection init failed, the connection error was not providing any meaningful information. This now adds an error log displaying the exception.

[oliemansm]

Thanks for your contribution!

[guilhermeblanco]

@oliemansm please let me know if there's anything I can assist here.

[oliemansm]

Why did you add the : {} part here? Since the way it was worked just fine letting it print the stack trace.

[oliemansm]

Why did you add the : {} part here? Since the way it was worked just fine letting it print the stack trace.