Fix @ExceptionHandler

[Sam-Kruglov]

related to #305 but it has become stale.
@oliemansm could you, please, take a look?

[Sam-Kruglov]

GraphQLErrorHandlerTest failed

[Sam-Kruglov]

Not sure if getContext().publishEvent(new ApplicationReadyEvent(new SpringApplication(), new String[0], getContext())); the best way but manually starting up spring context is also not the best way, so, at least it fits the rest of the code.
Please, consider using ApplicationContextRunner

[Sam-Kruglov]

May I also propose that GraphQLErrorHandlerFactory does not deal with DefaultGraphQLErrorHandler? So that it is more flexible for the client to configure the default one.
Maybe return List<GraphQLErrorFactory>

[Sam-Kruglov]

Another suggestion: make GraphQLErrorFromExceptionHandler and GraphQLErrorFactory public so that I can change the fallback values. E.g. I always want an error code in extensions, so I would change GenericGraphQLError and ThrowableGraphQLError at least

[oliemansm]

@Sam-Kruglov Just merged the other PR dealing with the same issue. Is there anything in this PR still relevant or has this now become obsolete?

[Sam-Kruglov]

Obsolete now. Thanks!