Fix pre-existing HintCode.UNNECESSARY_TYPE_CHECK_TRUE
diff --git a/lib/src/server.dart b/lib/src/server.dart
index ac34edf..afcc4ca 100644
--- a/lib/src/server.dart
+++ b/lib/src/server.dart
@@ -309,7 +309,6 @@
       try {
         return await iterator.current(params);
       } on RpcException catch (error) {
-        if (error is! RpcException) rethrow;
         if (error.code != error_code.METHOD_NOT_FOUND) rethrow;
         return _tryNext();
       }