title: IncompatibleClassChangeError: Class 'java.lang.VirtualMachineError' does not implement interface 'java.lang.CharSequence'
body: <p>I am having weird problems with my code and I cannot explain anything that's happening. It's crashing on Marshmallow but not on Nougat which makes this more bizarre.</p>
  
  <p>I can point to a line where the error occurs but the error itself is not clear. I am not sure what is crashing and how to prevent it. Here are the details:</p>
  
  <p>The crash happens when I try to make a call to the server. To do this, I use <code>Retrofit</code> alongside <code>RxJava</code> and I do this in Kotlin. Here is my code:</p>
  
  <pre><code>fun login(username: String, password: String, callback: Login.OnLoginListener) {
      RestClient.getInstance().service
      .loginUser( //&lt;- This line is crashing for no apparent reason
              Utils.RequestBodyParser.parseString(username),
              Utils.RequestBodyParser.parseString(password)
      )
      .subscribeOn(Schedulers.io())
      .observeOn(AndroidSchedulers.mainThread())
      .subscribe(
          { success -&gt;
              (
              if (success.status)
                  callback.onLoginSuccess()
              else
                  callback.onLoginError()
              )
          },
          { error -&gt;
              GenericErrorHandler.handleError(error, callback.retrieveContext())
          }
      )
  }
  </code></pre>
  
  <p>Here is the logcat output:</p>
  
  <pre><code>java.lang.IncompatibleClassChangeError: Class 'java.lang.VirtualMachineError' does not implement interface 'java.lang.CharSequence' in call to 'java.lang.String java.lang.CharSequence.toString()' (declaration of 'java.lang.Throwable' appears in /system/framework/core-libart.jar)
    at fi.hohtolabs.kuuratablet.network.WebController$Companion.login(WebController.kt:19)
    at fi.hohtolabs.kuuratablet.presenter.LoginPresenter.login(LoginPresenter.kt:31)
    at fi.hohtolabs.kuuratablet.dialog.LoginDialog.lambda$onResume$2$LoginDialog(LoginDialog.java:74)
    at fi.hohtolabs.kuuratablet.dialog.LoginDialog$$Lambda$2.onClick(Unknown Source)
    at android.view.View.performClick(View.java:5198)
    at android.view.View$PerformClick.run(View.java:21147)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
  </code></pre>
  
  <p>Does anybody have any suggestions on what I should do? (I tried cleaning, rebuilding, restarting and invalidating caches, deleted the .gradle folder and all other stuff like that, nothing helps)</p>