Fix server crash on iOS requests

Sources/App/Middleware/AppStoreAuthenticator.swift

@@ -64,6 +64,7 @@ struct AppStoreAuthenticator: HBAsyncAuthenticator {
         //    (in the iOS and macOS client app: Bundle.main.appStoreReceiptURL)
         //    However, the receipt is not available when testing in Xcode Sandbox,
         //    so the server accepts a transaction Id in sandbox mode as well
+        let request = try await request.collateBody().get()        
         guard let buffer = request.body.buffer, let body = buffer.getString(at: buffer.readerIndex, length: buffer.readableBytes) else {
             request.logger.error("/appstore invoked without app store receipt or transaction id in body")
             throw HBHTTPError(.badRequest)