Updated the logic for the background fetch timeout

Updated the logic for the background fetch timeout to happen in the AppDelegate and be based on a system property to avoid a few edge-cases
Removed the ID Blinding error handling 'e' suffix (as it's not actually part of the error)

Session/Meta/AppDelegate.swift

@@ -195,11 +195,43 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterD
         // Resume database
         NotificationCenter.default.post(name: Database.resumeNotification, object: self)
         
+        // Background tasks only last for a certain amount of time (which can result in a crash and a
+        // prompt appearing for the user), we want to avoid this and need to make sure to suspend the
+        // database again before the background task ends so we start a timer that expires 1 second
+        // before the background task is due to expire in order to do so
+        let cancelTimer: Timer = Timer.scheduledTimerOnMainThread(
+            withTimeInterval: (application.backgroundTimeRemaining - 1),
+            repeats: false
+        ) { timer in
+            timer.invalidate()
+            
+            guard BackgroundPoller.isValid else { return }
+            
+            BackgroundPoller.isValid = false
+            
+            // Suspend database
+            NotificationCenter.default.post(name: Database.suspendNotification, object: self)
+            
+            SNLog("Background poll failed due to manual timeout")
+            completionHandler(.failed)
+        }
+        
+        // Flag the background poller as valid first and then trigger it to poll once the app is
+        // ready (we do this here rather than in `BackgroundPoller.poll` to avoid the rare edge-case
+        // that could happen when the timeout triggers before the app becomes ready which would have
+        // incorrectly set this 'isValid' flag to true after it should have timed out)
+        BackgroundPoller.isValid = true
+        
         AppReadiness.runNowOrWhenAppDidBecomeReady {
             BackgroundPoller.poll { result in
+                guard BackgroundPoller.isValid else { return }
+                
+                BackgroundPoller.isValid = false
+                
                 // Suspend database
                 NotificationCenter.default.post(name: Database.suspendNotification, object: self)
                 
+                cancelTimer.invalidate()
                 completionHandler(result)
             }
         }

Session/Utilities/BackgroundPoller.swift

@@ -9,11 +9,9 @@ import SessionUtilitiesKit
 
 public final class BackgroundPoller {
     private static var promises: [Promise<Void>] = []
-    private static var isValid: Bool = false
+    public static var isValid: Bool = false
 
     public static func poll(completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
-        BackgroundPoller.isValid = true
-        
         promises = []
             .appending(pollForMessages())
             .appending(contentsOf: pollForClosedGroupMessages())
@@ -43,33 +41,18 @@ public final class BackgroundPoller {
                     }
             )
         
-        // Background tasks will automatically be terminated after 30 seconds (which results in a crash
-        // and a prompt to appear for the user) we want to avoid this so we start a timer which expires
-        // after 25 seconds allowing us to cancel all pending promises
-        let cancelTimer: Timer = Timer.scheduledTimerOnMainThread(withTimeInterval: 25, repeats: false) { timer in
-            timer.invalidate()
-            BackgroundPoller.isValid = false
-            
-            guard promises.contains(where: { !$0.isResolved }) else { return }
-            
-            SNLog("Background poll failed due to manual timeout")
-            completionHandler(.failed)
-        }
-        
         when(resolved: promises)
             .done { _ in
                 // If we have already invalidated the timer then do nothing (we essentially timed out)
-                guard cancelTimer.isValid else { return }
+                guard BackgroundPoller.isValid else { return }
                 
-                cancelTimer.invalidate()
                 completionHandler(.newData)
             }
             .catch { error in
                 // If we have already invalidated the timer then do nothing (we essentially timed out)
-                guard cancelTimer.isValid else { return }
+                guard BackgroundPoller.isValid else { return }
                 
                 SNLog("Background poll failed due to error: \(error)")
-                cancelTimer.invalidate()
                 completionHandler(.failed)
             }
     }

SessionMessagingKit/Sending & Receiving/Pollers/OpenGroupPoller.swift

@@ -202,7 +202,7 @@ extension OpenGroupAPI {
                 case .httpRequestFailedAtDestination(let statusCode, let data, _) = error,
                 statusCode == 400,
                 let dataString: String = String(data: data, encoding: .utf8),
-                dataString.contains("Invalid authentication: this server requires the use of blinded idse")
+                dataString.contains("Invalid authentication: this server requires the use of blinded ids")
             else { return Promise.value(false) }
             
             let (promise, seal) = Promise<Bool>.pending()