Mysterious Bad Access

BadAccess.swift

import Cocoa

public func with<T>(_ item: T, update: (inout T) throws -> Void) rethrows -> T {
    var this = item; try update(&this); return this
}

let path = with(CGMutablePath()) { // <---  Bad Access
    $0.move(to: CGPoint(x: 0, y: 0))
    $0.addLine(to: CGPoint(x: 100, y: 100))
}