- var x1 = series[0][0];
- if (!this.minxval || x1 < this.minxval) this.minxval = x1;
-
- var x2 = series[series.length - 1][0];
- if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
+ if (series.length > 1) {
+ var x1 = series[0][0];
+ if (!this.minxval || x1 < this.minxval) this.minxval = x1;
+
+ var x2 = series[series.length - 1][0];
+ if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
+ }