fix biz exception cast issue (#1522)

Co-authored-by: liujianjun.ljj <liujianjun.ljj@antgroup.com>

Author: EvenLjj

remoting/remoting-triple/src/main/java/com/alipay/sofa/rpc/server/triple/GenericServiceImpl.java

@@ -120,7 +120,11 @@ public StreamObserver<Request> genericBiStream(StreamObserver<Response> response
 
             SofaResponse sofaResponse = invoker.invoke(sofaRequest);
 
-            SofaStreamObserver<Object> clientHandler = (SofaStreamObserver<Object>) sofaResponse.getAppResponse();
+            Object appResponse = sofaResponse.getAppResponse();
+            if (appResponse instanceof Exception) {
+                throw (Exception) appResponse;
+            }
+            SofaStreamObserver<Object> clientHandler = (SofaStreamObserver<Object>) appResponse;
 
             return new StreamObserver<Request>() {
                 private volatile Serializer serializer    = null;