After some investigation, this appears to be a related to an issue with my schema where the server is declaring a field exists of type
string, whereas the client does not have any such awareness of this. For some reason, when the schema is being initially applied,
RemoveProperty schema change is being applied to it in Realm's initial schema creation. This is falling afoul of some logic error I believe ( I haven't been able to successfully breakpoint in Realm core to figure out why ).
Needless to say, "Unsupported Instruction" is not a very helpful error. There should be a better explanation of why things are failing here. I feel like I'm falling afoul of some weird edge case implied by the comment in
// Note that in normal operation none of these will be hit, as if we're
// creating the initial tables there shouldn't be anything to update.
// Implementing these makes us better able to handle weird
// not-quite-correct files produced by other things and has no obvious
as my initial schema creation is repeatedly hitting
AddIndex calls, perhaps implying a schema disagreement or drift between the client and server. If that's the case though I would have expected some sort of indicator or error message rather than "Unsupported Instruction".