script output extension creates 0 size file

Script output extension doesn't allow cancellation of export from export script. So even in case when no output is generated inkscape creates 0 size file
It's caused by script.cpp save routine where you can find those lines of code:
    file_listener fileout;
    execute(command, params, tempfilename_in, fileout);

    std::string lfilename = Glib::filename_from_utf8(filenameArg);
    bool success = fileout.toFile(lfilename);

execute function returns correctly 0 in case there is no output (stdout), but the return value is never checked and new file is always created.