Fix race conditions on first launch

ios/App/Shared/player/AudioPlayer.swift

@@ -261,6 +261,12 @@ class AudioPlayer: NSObject {
     }
     
     public func setPlaybackRate(_ rate: Float, observed: Bool = false) {
+        // Handle a race condition on first launch
+        guard self.status != -1 else {
+            NSLog("Did not set playback rate as player is not initialized")
+            return
+        }
+        
         if self.audioPlayer.rate != rate {
             NSLog("setPlaybakRate rate changed from \(self.audioPlayer.rate) to \(rate)")
             self.audioPlayer.rate = rate

ios/App/Shared/util/PlayerEvents.swift

@@ -14,4 +14,5 @@ enum PlayerEvents: String {
     case sleepEnded = "com.audiobookshelf.app.player.sleep.ended"
     case failed = "com.audiobookshelf.app.player.failed"
     case localProgress = "com.audiobookshelf.app.player.localProgress"
+    case playerUserInterfaceReady = "com.audiobookshelf.app.player.playerUserInterfaceReady"
 }