Improved Exception Handling of Exceptions during Validation Phase

Exceptions during the validation phase of a GraphQL query resulted in a HTTP 500 error for a validation error, e.g. "maximum query depth exceeded". This was caused by an incorrect exception handling in the PreparsedDocumentProvider of CaasConfig. The bugfix now handles all Exceptions, returning a HTTP 200 OK with the correct GraphQL error message.

(CMS-21011)

Bugfix: Extending a GraphQL Enum causes a ClassCastException

Extending a GraphQL Enum caused a ClassCastException while server start. This bug was fixed.

(CMS-20600)