php 7.0 - error with graph_svg.php (Array to string conversion in line 48)

[rcmcronny]

No svg graphs are shown, after digging into it, the svg contains a notice like

Notice: Array to string conversion in $webroot/vnstat/graph_svg.php on line 48

so as a quick workaround, these changes to the config.php file are helping, as long as this is not fixed

-error_reporting(E_ALL | E_NOTICE);
+error_reporting(E_ALL & ~E_NOTICE);