Hi.
If Sixx wants to open an empty file it crashes but adding a guard close 
prevents this.
It's currently in the SPrevayler changeset so it would be kind if you 
tell me when somebody fixed it in the sixx package.

SixxReadStream>>initialize

    (stream size = 0) ifTrue: [position_0. limit_0. ^self.]. "Guarding 
clause"
    contextDictionary := IdentityDictionary new.
    position := 0.
    sixxElements := self parseStream: stream.
    limit := sixxElements isNil
                ifTrue: [0]
                ifFalse: [sixxElements size].
    cachedObjects := Dictionary new

Regards
Marco