Add workaround for Optional JSONEncoding errors

Sources/Apollo/JSONStandardTypeConversions.swift

@@ -105,6 +105,22 @@ extension Optional: JSONEncodable {
       return NSNull()
     case .some(let wrapped as JSONEncodable):
       return wrapped.jsonValue
+
+    // WORKAROUND: For reasons I don't totally understand, when the underlying type is `Any`,
+    // even though all of these conform to `JSONEncodable`, the `as JSONEncodable` above
+    //  fails, and we need to handle them individually.
+    case .some(let wrapped as String):
+      return wrapped.jsonValue
+    case .some(let wrapped as Int):
+      return wrapped.jsonValue
+    case .some(let wrapped as Double):
+      return wrapped.jsonValue
+    case .some(let wrapped as Bool):
+      return wrapped.jsonValue
+    case .some(let wrapped as [String: Any?]):
+      return wrapped.jsonValue
+    case .some(let wrapped as [Any?]):
+      return wrapped.jsonValue
     default:
       fatalError("Optional is only JSONEncodable if Wrapped is")
     }
@@ -129,6 +145,16 @@ extension Dictionary: JSONEncodable {
   }
 }
 
+extension Dictionary: JSONDecodable {
+    public init(jsonValue value: JSONValue) throws {
+        guard let dictionary = value as? Dictionary else {
+            throw JSONDecodingError.couldNotConvert(value: value, to: Dictionary.self)
+        }
+
+        self = dictionary
+    }
+}
+
 extension Array: JSONEncodable {
   public var jsonValue: JSONValue {
     return map() { element -> (JSONValue) in

Tests/ApolloTests/JSONTests.swift

@@ -38,4 +38,39 @@ class JSONTests: XCTestCase {
     XCTAssertFalse(value ~= JSONDecodingError.nullValue)
     XCTAssertFalse(value ~= JSONDecodingError.missingValue)
   }
+
+  func testJSONDictionaryEncodingAndDecoding() throws {
+    let jsonString = """
+{
+  "a_dict": {
+    "a_bool": true,
+    "another_dict" : {
+      "a_double": 23.1,
+      "an_int": 8,
+      "a_string": "LOL wat"
+    },
+    "an_array": [
+      "one",
+      "two",
+      "three"
+    ],
+    "a_null": null
+  }
+}
+"""
+    let data = try XCTUnwrap(jsonString.data(using: .utf8))
+    let json = try JSONSerializationFormat.deserialize(data: data)
+    XCTAssertNotNil(json)
+
+    let dict = try Dictionary<String, Any?>(jsonValue: json)
+    XCTAssertNotNil(dict)
+
+    let reserialized = try JSONSerializationFormat.serialize(value: dict)
+    XCTAssertNotNil(reserialized)
+
+    let stringFromReserialized = try XCTUnwrap(String(bytes: reserialized, encoding: .utf8))
+    XCTAssertEqual(stringFromReserialized, """
+{"a_dict":{"a_bool":1,"a_null":null,"an_array":["one","two","three"],"another_dict":{"a_double":23.100000000000001,"a_string":"LOL wat","an_int":8}}}
+""")
+  }
 }