BUGFIX: Prevent division by zero in sparkline rendering (#39)

Prevent division by zero in sparkline rendering when `max` is 0 for whatever reason.

In this case a 0 value will be rendered now instead of crashing the whole content release.

Author: JamesAlias

Classes/Utility/Sparkline.php

@@ -13,6 +13,11 @@ class Sparkline
      */
     private static function getY($max, $height, $diff, $value)
     {
+        // prevent division by zero
+        if ($max === 0) {
+            return round(floatval(($height + $diff)), 2);
+        }
+
         return round(floatval(($height - ($value * $height / $max) + $diff)), 2);
     }
 
@@ -58,4 +63,4 @@ public static function sparkline($svgClass, $values, $lineColor = '#aaa', $fillC
         return '<!-- Generated with https://github.com/jxxe/sparkline/ -->' . $svg;
     }
 
-}
+}