iOS app crashes if a NetStream is referenced by a class variable when app is brought to foreground

Consistently happens on AIR 32 (tried also 27 and 31), iOS 12 and 8.

A video of this happening on both iOS8 and iOS12: airiosbug.mp4 - Google Drive

Just create a NetConnection and a NetStream.

If class has a variable referncing the NetStream, if app is brought to background and then to foreground, it crashes immediately.

If NetStrean is not referenced, app doesn't crash.

Crash log infact reports a null pointer.

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)

Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000

Note that app works perfectly and for a long time if not brought to background and back to foreground again. Crashes only when brought back to foreground.

You can download source code here: https://drive.google.com/open?id=1s92-Wv99dechTZgqRxNMpf-C1SabxBNh

Here is the only code:

Commenting: "_ns = ns;" application does not crash.

package 
{
import flash.display.MovieClip;
import flash.net.NetConnection;
import flash.net.NetStream;
import flash.text.TextField;
/**
* ...
* @author Pippo Gregoretti
*/
public class MainAppDebug extends MovieClip 
{
private var _tf:TextField;
private var _ns:NetStream;   
public function MainAppDebug() 
{
super();
trace("Debugging AIR application.");
//(_debugConsole as DebugConsole).show();
_tf = new TextField();
_tf.border = true;
_tf.width = stage.stageWidth;
_tf.height = stage.stageHeight;
_tf.multiline = true;
addChild(_tf);
addText("Debugging AIR Application");
addText("Creating NetStreams...");
var nc:NetConnection = new NetConnection();
nc.connect(null);
var ns:NetStream = new NetStream(nc);
/* THIS IS THE CULPRIT. COMMENT "_ns = ns" AND APP WILL NOT CRASH */
_ns = ns;
}
private function addText(t:String):void {
_tf.appendText(t + "\n");
}
}
}