title: RxSwift crash EXC_BAD_ACCESS, when OnNext called on subject
body: <p>I have a weird crash that I managed to reproduce in skeleton app.
  I have a framework which uses RxSwift az a cocoapod dependency.
  It has a simple class defined:</p>
  <pre><code>public final class FWSupplier {
      public let psubject = PublishSubject&lt;Int&gt;()
      public let bsubject = BehaviorSubject&lt;Int&gt;(value: 0)
      public init() { }
      public func triggerBehaviour() {
          self.bsubject.onNext(1)
      }
  
      public func triggerPublish() {
          self.psubject.onNext(1)
      }
  }
  </code></pre>
  <p>I build the framework as an XCFramework and import it into a host app.
  In the app I simply instantiate the FWSupplier in a view controller and call triggerPublish and it crashes.</p>
  <pre><code>class ViewController: UIViewController {
      @IBOutlet var label: UILabel!
      let supplier = FWSupplier()
  
      override func viewDidLoad() {
          super.viewDidLoad()
          supplier.triggerPublish()
      }
  }
  </code></pre>
  <p>Anyone have any idea what I'm doing wrong?
  <a href="https://i.stack.imgur.com/pqDb8.png" rel="nofollow noreferrer">Screenshot of error</a>
  <a href="https://i.stack.imgur.com/waI8U.png" rel="nofollow noreferrer">Screenshot of stack</a></p>