I had a look and it seems SummarizeTransaction accepts a NULL argument. @dvolgyes I'd prefer to set the value to NULL only when case PROMISE_RESULT_WARN, but your current fix is good enough for me anyway.

@tzz In general, practices that shut off compiler warnings are best to be avoided. By generally initialising on every declaration, you stop getting all relevant warnings. Of course on specific cases it's actually valid to shut-off the stupid compiler... ;-)