refactor: keep original code

Author: vvisionnn

FirebaseCore/Internal/Sources/HeartbeatLogging/RingBuffer.swift

@@ -26,6 +26,10 @@ struct RingBuffer<Element>: Sequence {
     case outOfBoundsPush(pushIndex: Array<Element?>.Index, endIndex: Array<Element?>.Index)
 
     var errorDescription: String? {
+      return (errorDescription as String)
+    }
+
+    var errorDescription: String {
       switch self {
       case let .outOfBoundsPush(pushIndex, endIndex):
         return "Out-of-bounds push at index \(pushIndex) to ring buffer with" +