fix: removed the possibility of concurrent webauth transactions to ha…

…ndle continuation misuse

Auth0/TransactionStore.swift

@@ -14,7 +14,10 @@ class TransactionStore {
         return isResumed
     }
 
+
+    /// Calling store would cancel existing transactions if any, and then would set the supplied transaction as the current one.
     func store(_ transaction: AuthTransaction) {
+        self.cancel()
         self.current = transaction
     }