Unref the call stack in read_service_config even on error.

src/core/ext/client_config/client_channel.c

@@ -830,7 +830,7 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
   // If this is an error, there's no point in looking at the service config.
-  if (error != GRPC_ERROR_NONE) return;
+  if (error == GRPC_ERROR_NONE) {
     // Get the method config table from channel data.
     gpr_mu_lock(&chand->mu);
     grpc_method_config_table *method_config_table = NULL;
@@ -869,6 +869,7 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
       }
       grpc_method_config_table_unref(method_config_table);
     }
+  }
   GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "read_service_config");
 }