onError abstract method Null safety

Deregistration onError(
  1. dynamic onError(
    1. OperationError
    )
)

Specifies the object that will be invoked if the deregistration failed.

IMPORTANT
Providing the onError is required.

Params:

Returns: a Deregistration object.

Implementation

Deregistration onError(Function(OperationError) onError);