SessionAwareHandle wrapped the base's WorkerHandle but never overrode
charterReceipt(), so it silently inherited the interface default (null)
while the real receipt sat on its delegate. sol/terra never got a
charterSource/charterSha256 roster row.
Deletes the default so every PeerHandle must answer explicitly; the
compiler now catches this class of gap instead of a roster field
quietly going missing.
Dai Ha
35ade14630