feat(kernel): Add Error as a possible params type of CommandReply.

[grypez]

It seems reasonable to me that any reply except 'pong' could be an error. Once we get custom error classes we could set the ErrorType to the appropriate union for each CommandReply element.

Changes

@ocap/kernel

• Realizes CommandReply as a union of the new CommandReplyLike type

type CommandReplyLike<
  Method extends CommandMethod,
  Data extends CommandParams,
  ErrorType extends Error = never,
> = {
  method: Method;
  params: Data|ErrorType;
};

• Permits CommandMethod.KVGet to return an Error as its params

@ocap/extension

• Introduces an asError routine to cast problems to Errors (reference)

[FUDCo]

Ooh ooh!