"lldb" crash with XCODE & ARKIT : 0 __ UpdateAudioTransform - ios

Question

I have written a game using ARKIT that pops up random nodes (with drones) in the 3d space around the player, using ARKIT, and I get an incomprehensible crash, as only thing in the console is "lldb" , and the rest of the crash details are on the screenshot attached (I am still a newbie in Swift so not able to debug it).
The crash happens when there's a lot of nodes on the screen (maybe 20-30) and the FPS drops - ie happens "mid - game" and the FPS drops a lot.
Can someone point me to the right direction for this crash?
The part of the code that is in my opinion relevant is the function that spawns the random 3d nodes (they also have SCNActions attached that play sounds when they're tapped - perhaps this could be relevant as the left hand side debugger opens with that line highlighted when the crash occurs, as per the photo attached). In case it is also relevant, the program uses some SCNParticleSystem calls as well. Attaching relevant code, and also the snapshot of the crash screen:
var droneSound : SCNAudioSource()
override func viewDidLoad() {
super.viewDidLoad()
droneSound = SCNAudioSource(named: "Sounds/drone1.wav")!
playDroneSound = SCNAction.playAudio(self.droneSound, waitForCompletion: true)
}
func startGame() {
DispatchQueue.main.async {
self.spawnTimer = Timer.scheduledTimer(timeInterval: TimeInterval(self.randomFloat(min: 2.5, max: 5)), target: self, selector: #selector(self.spawnDronesInterim), userInfo: nil, repeats: true)
}
}
#objc func spawnDronesInterim() {
for _ in 0...5 {
spawnDrone()
}
}
#objc func spawnDrone() {
let newDroneScene = SCNScene(named: "Ar.scnassets/DroneScene.scn")!
var newDroneNode = newDroneScene.rootNode.childNode(withName: "Drone", recursively: false)!
newDroneNode.name = "Drone\(self.droneCounter)"
newDroneNode = newDroneScene.rootNode.childNode(withName: "Drone\(self.droneCounter)", recursively: false)!
newDroneNode.position.x = newDroneNode.presentation.position.x + self.randomFloat(min: -10, max: 10)
newDroneNode.position.y = newDroneNode.presentation.position.y + self.randomFloat(min: -1, max: 5)
newDroneNode.position.z = newDroneNode.presentation.position.z + self.randomFloat(min: -10, max: 10)
let move1 = SCNAction.move(to: SCNVector3((self.randomFloat(min: -7, max: 7)), (self.randomFloat(min: 1, max: 5)), (self.randomFloat(min: -7, max: 7))), duration: 15)
let disappearMove = SCNAction.move(to: SCNVector3((self.randomFloat(min: -10, max: 10)), (self.randomFloat(min: 1, max: 5)), (self.randomFloat(min: -10, max: 10))), duration: 3)
let rotateAction = SCNAction.run { (SCNNode) in
let rotate = SCNAction.rotateBy(x: 0, y: CGFloat(360.degreesToRadians), z: 0, duration: 2)
newDroneNode.runAction(rotate)
}
let removeIt = SCNAction.removeFromParentNode()
let sequence = SCNAction.sequence([waitFive,move1,rotateAction,waitFive,disappearMove,waitTwo,removeIt])
newDroneNode.runAction(sequence)
self.sceneView.scene.rootNode.addChildNode(newDroneNode)
if self.droneCounter >= 5 {
self.sceneView.scene.rootNode.childNode(withName: "Drone\(self.droneCounter)", recursively: true)!.runAction(SCNAction.repeatForever(self.playDroneSound))
}
self.droneCounter += 1
}
when user taps on one of the 3d nodes, this gets called:
func handleExplosion (node : SCNNode) {
self.sceneView.scene.rootNode.childNode(withName: node.name!, recursively: true)!.runAction(self.playExplosionSound)
node.opacity = 0
print (self.sceneView.scene.rootNode.position)
let confetti = SCNParticleSystem(named: "Ar.scnassets/confetti.scnp", inDirectory: nil)
confetti?.loops = false
confetti?.particleLifeSpan = 1.5
confetti?.emitterShape = node.geometry
let confettiNode = SCNNode()
confettiNode.addParticleSystem(confetti!)
confettiNode.position = node.presentation.position
self.sceneView.scene.rootNode.addChildNode(confettiNode)
let fire = SCNParticleSystem(named: "Ar.scnassets/fire", inDirectory: nil)
fire?.loops = false
fire?.particleLifeSpan = 0.1
fire?.emitterShape = node.geometry
let fireNode = SCNNode()
fireNode.addParticleSystem(fire!)
fireNode.position = node.presentation.position
self.sceneView.scene.rootNode.addChildNode(fireNode)
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
node.removeFromParentNode()
self.killedLabel.text = "Killed: \(self.killedCount)"
self.dronesOut -= 1
}
}
Any pointer to the right direction for solving this crash would be greatly appreciated]1