Merge pull request #20466 from soheilhy/fix-call-op-str

Fix the internal build and test failure introduced in #20329

include/grpcpp/impl/codegen/call_op_set.h

@@ -772,9 +772,8 @@ class CallOpClientRecvStatus {
 
   void FinishOp(bool* /*status*/) {
     if (recv_status_ == nullptr || hijacked_) return;
-    if (status_code_ == StatusCode::OK) {
+    if (static_cast<StatusCode>(status_code_) == StatusCode::OK) {
       *recv_status_ = Status();
-      GPR_CODEGEN_DEBUG_ASSERT(GRPC_SLICE_IS_EMPTY(error_message_));
       GPR_CODEGEN_DEBUG_ASSERT(debug_error_string_ == nullptr);
     } else {
       *recv_status_ =
@@ -784,12 +783,14 @@ class CallOpClientRecvStatus {
                      : grpc::string(GRPC_SLICE_START_PTR(error_message_),
                                     GRPC_SLICE_END_PTR(error_message_)),
                  metadata_map_->GetBinaryErrorDetails());
-      g_core_codegen_interface->grpc_slice_unref(error_message_);
       if (debug_error_string_ != nullptr) {
         client_context_->set_debug_error_string(debug_error_string_);
         g_core_codegen_interface->gpr_free((void*)debug_error_string_);
       }
     }
+    // TODO(soheil): Find callers that set debug string even for status OK,
+    //               and fix them.
+    g_core_codegen_interface->grpc_slice_unref(error_message_);
   }
 
   void SetInterceptionHookPoint(