         }
 
         log("failed: \(incompatibility)")
-        throw PubgrubError._unresolvable(incompatibility, state)
+        throw PubgrubError._unresolvable(incompatibility, state.incompatibilities)
     }
 
     /// Does a given incompatibility specify that version solving has entirely

            }
        }

        var state: State? {
            switch self {
            case ._unresolvable(_, let state):
                return state
            case .unresolvable:
                return nil
            }

}

extension PubgrubDependencyResolver {
    public enum PubgrubError: Swift.Error, CustomStringConvertible {
        case _unresolvable(Incompatibility, [DependencyResolutionNode: [Incompatibility]])
        case unresolvable(String)

        public var description: String {
