Hopefully fix threading issue

SignalServiceKit/src/Loki/API/LokiAPI+SwarmAPI.swift

@@ -121,7 +121,7 @@ public extension LokiAPI {
 internal extension Promise {
     
     internal func handlingSwarmSpecificErrorsIfNeeded(for target: LokiAPITarget, associatedWith hexEncodedPublicKey: String) -> Promise<T> {
-        return recover(on: DispatchQueue.global()) { error -> Promise<T> in
+        return recover(on: LokiAPI.errorHandlingQueue) { error -> Promise<T> in
             if let error = error as? NetworkManagerError {
                 switch error.statusCode {
                 case 0, 400, 500, 503:
@@ -130,7 +130,6 @@ internal extension Promise {
                     let newFailureCount = oldFailureCount + 1
                     LokiAPI.failureCount[target] = newFailureCount
                     print("[Loki] Couldn't reach snode at: \(target); setting failure count to \(newFailureCount).")
-                    Analytics.shared.track("Unreachable Snode")
                     if newFailureCount >= LokiAPI.failureThreshold {
                         print("[Loki] Failure threshold reached for: \(target); dropping it.")
                         LokiAPI.dropIfNeeded(target, hexEncodedPublicKey: hexEncodedPublicKey) // Remove it from the swarm cache associated with the given public key
@@ -140,7 +139,6 @@ internal extension Promise {
                 case 421:
                     // The snode isn't associated with the given public key anymore
                     print("[Loki] Invalidating swarm for: \(hexEncodedPublicKey).")
-                    Analytics.shared.track("Migrated Snode")
                     LokiAPI.dropIfNeeded(target, hexEncodedPublicKey: hexEncodedPublicKey)
                 case 432:
                     // The PoW difficulty is too low

SignalServiceKit/src/Loki/API/LokiAPI.swift

@@ -5,6 +5,7 @@ public final class LokiAPI : NSObject {
     private static var syncMessageTimestamps: [String:Set<UInt64>] = [:]
     public static var lastDeviceLinkUpdate: [String:Date] = [:] // Hex encoded public key to date
     @objc public static var userHexEncodedPublicKeyCache: [String:Set<String>] = [:] // Thread ID to set of user hex encoded public keys
+    public static let errorHandlingQueue = DispatchQueue(label: "errorHandlingQueue")
     
     // MARK: Convenience
     internal static let storage = OWSPrimaryStorage.shared()

SignalServiceKit/src/Loki/API/LokiLongPoller.swift

@@ -69,7 +69,7 @@ public final class LokiLongPoller : NSObject {
             let nextSnode = unusedSnodes.randomElement()!
             usedSnodes.insert(nextSnode)
             print("[Loki] Opening long polling connection to \(nextSnode).")
-            longPoll(nextSnode, seal: seal).catch(on: DispatchQueue.global()) { [weak self] error in
+            longPoll(nextSnode, seal: seal).catch(on: LokiAPI.errorHandlingQueue) { [weak self] error in
                 print("[Loki] Long polling connection to \(nextSnode) failed; dropping it and switching to next snode.")
                 LokiAPI.dropIfNeeded(nextSnode, hexEncodedPublicKey: userHexEncodedPublicKey)
                 self?.openConnectionToNextSnode(seal: seal)