Check if inner exception is of type GraphQLError in DefaultGraphQLErrorHandler

[karl-run]

According to the graphql-java documentation, "Error while fetching data", it says:

If the exception you throw is itself a GraphqlError then it will transfer the message and custom extensions attributes from that exception into the ExceptionWhileDataFetching object. This allows you to place your own custom attributes into the graphql error that is sent back to the caller.

In graphql.execution.SimpleDataFetcherExceptionHandler, all exceptions are wrapped in a graphql.ExceptionWhileDataFetching. To maintain the functionality as described in the graphql-java-docs we need to check if the inner exception in graphql.servlet.DefaultGraphQLErrorHandler.java:47 is of type GraphQLError, in which case it should be a client error.

I'm not 100% sure of these assumptions, but in our case this would make sense. If not, we would have no way of passing errors through to the caller without implementing our own ExecutionStrategy.

Relates to #50.

[apottere]

Good catch, thanks for the PR! I looked over the docs and this does look like the right thing to do.

[apottere]

This is released in 4.6.1, syncing now.