KeyedMapper segfault

JSONKey.swift

import Foundation

public protocol JSONKey: RawRepresentable, Hashable {
    var stringValue: String { get }
}

extension JSONKey where Self.RawValue == String {
    public var stringValue: String {
        return rawValue
    }
}

KeyedMapper.swift

import Foundation

public struct KeyedMapper<Object: Mappable> {
    public let JSON: [AnyHashable : Any]

    public init(JSON: [AnyHashable : Any], type: Object.Type) {
        self.JSON = JSON
    }
}

Mappable.swift

import Foundation

public protocol Mappable {
    associatedtype Key: JSONKey

    init(map: KeyedMapper<Self>) throws
}

1.	While reading from /Users/Blair/Library/Developer/Xcode/DerivedData/KeyedMapperSegFault-cbmkkertbzqysabwirlimgurjxaj/Build/Intermediates/KeyedMapperSegFault.build/Debug-iphonesimulator/KeyedMapperSegFault.build/Objects-normal/x86_64/KeyedMapper~partial.swiftmodule
2.	While deserializing decl #3 (STRUCT_DECL)
3.	While deserializing 'Object' (GenericTypeParamDecl #1) 
4.	While deserializing decl #6 (XREF)
5.	Cross-reference to module 'KeyedMapperSegFault'
	... Mappable
	... Key
6.	While loading members for 'Mappable' at <invalid loc>
7.	While deserializing 'init' (ConstructorDecl #4) 
8.	While deserializing decl #8 (PARAM_DECL)
9.	While deserializing decl #9 (XREF)
10.	Cross-reference to module 'KeyedMapperSegFault'
	... KeyedMapper
11.	While reading from /Users/Blair/Library/Developer/Xcode/DerivedData/KeyedMapperSegFault-cbmkkertbzqysabwirlimgurjxaj/Build/Intermediates/KeyedMapperSegFault.build/Debug-iphonesimulator/KeyedMapperSegFault.build/Objects-normal/x86_64/KeyedMapper~partial.swiftmodule
12.	While deserializing decl #3 (STRUCT_DECL)