NSMutableDictionary(contentsOf:error:) Bug (Fixed on Catalina)

NSMutableDictionaryBug.swift

import Foundation

let url = FileManager.default.temporaryDirectory.appendingPathComponent("test.plist")

func crashes() throws {
    try NSDictionary().write(to: url)
    let returned = try NSMutableDictionary(contentsOf: url, error: ())

    /// This will crash
    returned.setValue("Hello", forKey: "World")
}

func works() throws {
    try NSDictionary(dictionary: ["Key" : "InitialValue"]).write(to: url)
    let returned = try NSMutableDictionary(contentsOf: url, error: ())

    /// This will NOT crash
    returned.setValue("Hello", forKey: "World")
}

try? works()
print("works() succeeded")
try? crashes()