OperationException(linkException: ResponseFormatException(originalException: type 'Null' is not a subtype of type 'String' in type cast

[Routee]

if the backend throw a custom exception which message is null. This line:

error['message'] as String

will throw an excption. it's not the expected.

[knaeckeKami]

Actually, a message is required by the graphql spec

See https://spec.graphql.org/October2021/#sec-Errors.Error-result-format