SDK-1831 add a lock, just in case

Author: echo-branch

BranchSDK/Branch.m

@@ -2182,11 +2182,14 @@ - (void)initSafetyCheck {
 }
 
 - (void)initUserSessionAndCallCallback:(BOOL)callCallback sceneIdentifier:(NSString *)sceneIdentifier {
-    // Ignore lifecycle calls while init is deferred to a plugin runtime.
-    if (self.deferInitForPluginRuntime) {
-        //NSString *debug = [NSString stringWithFormat:@"Init is deferred, ignoring call: %@", NSThread.callStackSymbols];
-        //BNCLogDebug(debug);
-        return;
+    
+    // ignore lifecycle calls while waiting for a plugin runtime.
+    @synchronized (self) {
+        if (self.deferInitForPluginRuntime) {
+            //NSString *debug = [NSString stringWithFormat:@"Init is deferred, ignoring call: %@", NSThread.callStackSymbols];
+            //BNCLogDebug(debug);
+            return;
+        }
     }
 
     dispatch_async(self.isolationQueue, ^(){