Cluster "Illegal" still not implemented

[cryptax]

Hi - I know you're no longer supporting this project, but I've started looking into what modifications it would need for new versions.
I've fixed a couple of obvious things like the hash, snapshot kind (as mentioned in issue #8), but I'm having an issue with CIDs.

    raise ParseError(self.data_offset + self.data.tell(), 'Cluster "{}" still not implemented'.format(handler))
darter.core.ParseError: (719, 'Cluster "Illegal" still not implemented')

The VM snapshot has byte 0xc0 where we should read the first Cid, and that reads into value 0, which corresponds to Cid "Illegal". Any idea what's causing this? I'd love to hear if there's a detailed document on snapshot structure (byte per byte)...

From my understanding, the serialization of clusters has slightly changed and no longer begins with the CID, but with a predefined count, then CID, then object count. When I fix this, the parsing crashes in the next cluster

[000002d1]: DEBUG: read_cluster(): predef_count=64 cid=185 object_count=0
[000002d7]: DEBUG: read_cluster(): predef_count=2 cid=-62 object_count=0
raise ParseError(self.data_offset + self.data.tell(), 'Cluster "{}" still not implemented'.format(handler))
darter.core.ParseError: (727, 'Cluster "FfiInt32" still not implemented')

I thought perhaps Cid 0 was now valid, but no, source code still specifies it as invalid.

enum ClassId : intptr_t {
  // Illegal class id.
  kIllegalCid = 0,

My non-fonctional fork is here.