App Crashes When Observing Real Time Chat Data with Firebase-iOS - ios

Question

I am currently learning Swift and I decided to make an iOS messaging app using Firebase. I am using JSQMessageViewController as my chat template and everything is working fine except for the fact that the app crashes when two users talking to each other are in the chat room at the same time. I am getting this error near the bottom of the function below: "Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)"
Here is my code for observing and retrieving message data. I call this everytime the view appears:
private func observeMessages() {
messageRef = ref.child("ChatRooms").child(chatRoomId!).child("Messages")
let messageQuery = messageRef.queryLimited(toLast:25)
newMessageRefHandle = messageQuery.observe(.childAdded, with: { (snapshot) in
let messageData = snapshot.value as! Dictionary<String, AnyObject>
if let data = snapshot.value as? [String: AnyObject],
let id = data["sender_id"] as? String,
let name = data["name"] as? String,
let text = data["text"] as? String,
let time = data["time"] as? TimeInterval,
!text.isEmpty
{
if id != uid! {
let updateRead = ref.child("ChatRooms").child(self.chatRoomId!).child("Messages").child(snapshot.key)
updateRead.updateChildValues(["status":"read"])
}
if let message = JSQMessage(senderId: id, senderDisplayName: name, date: Date(timeIntervalSince1970: time), text: text)
{
self.messages.append(message)
self.finishReceivingMessage()
}
}else if let id = messageData["senderId"] as! String!,
let photoURL = messageData["photoURL"] as! String! { // 1
if let mediaItem = JSQPhotoMediaItem(maskAsOutgoing: id == self.senderId) {
self.addPhotoMessage(withId: id, key: snapshot.key, mediaItem: mediaItem)
if photoURL.hasPrefix("gs://") {
self.fetchImageDataAtURL(photoURL, forMediaItem: mediaItem, clearsPhotoMessageMapOnSuccessForKey: nil)
}
}
}else {
print("Error! Could not decode message data")
}
})
updatedMessageRefHandle = messageRef.observe(.childChanged, with: { (snapshot) in
let key = snapshot.key
//I am getting an error on this line
let messageData = snapshot.value as! Dictionary<String, String>
if let photoURL = messageData["photoURL"] as String! {
// The photo has been updated.
if let mediaItem = self.photoMessageMap[key] {
self.fetchImageDataAtURL(photoURL, forMediaItem: mediaItem, clearsPhotoMessageMapOnSuccessForKey: key)
}
}
})
}
Curious to what I might be doing wrong here. All help is appreciated!