We provide a hierarchy of errors which allow to clearly identify the problem if something went wrong:

• FLError
  • FLSerializationError
    • FLNotSerializable
    • FLObjectNotFound
    • FLObsolete
  • FLMaterializationError
    • FLBadSignature
    • FLBadVersion
    • FLClassNotFound
    • FLGlobalNotFound
    • FLMethodChanged
    • FLMethodNotFound

As most classes of Fuel, they have class comments that give an idea their meanings:

FLError

I represent an error produced during Fuel operation.

FLSerializationError

I represent an error happened during serialization.

FLNotSerializable

I represent an error which may happen while tracing in the graph an object that is forbidden of being serialized.

FLObjectNotFound

I represent an error which may happen during serialization, when trying to encode on the stream a reference to an object that should be encoded before, but it is not. This usually happens when the graph changes during serialization. Another possible cause is a bug in the analysis step of serialization.

FLObsolete

I am an error produced during serialization, signaled when trying to serialize an obsolete class as global. It is a prevention, because such class is likely to be absent during materialization.

FLMaterializationError

I represent an error happened during materialization.

FLBadSignature

I represent an error produced during materialization when the serialized signature doesn't match the materializer's signature (accessible via FLMaterializer>>signature). A signature is a byte prefix that should prefix a well-serialized stream.

FLBadVersion

I represent an error produced during materialization when the serialized version doesn't match the materializer's version (accessible via FLMaterializer>>version). A version is encoded in 16 bits and is encoded heading the serialized stream, after the signature.

FLClassNotFound

I represent an error produced during materialization when a serialized class or trait name doesn't exist.

FLGlobalNotFound

I represent an error produced during materialization when a serialized global name doesn't exist (at Smalltalk globals).

FLMethodChanged

I represent an error produced during materialization when is detected a change in the bytecodes of a method serialized as global. This error was born when testing the materialization of a BlockClosure defined in a method that changed. The test produced a VM crash.

FLMethodNotFound

I represent an error produced during materialization when a serialized method in a class or trait name doesn't exist (at Smalltalk globals).