Use the utility function for contour point usage.
MODIFY
src/contourFeature.js
src/contourFeature.js
@@ -129,8 +129,7 @@ var contourFeature = function (arg) {
minValue, maxValue, val, range, i, k;
var result = this.createMesh({
used: function (d, i) {
- var val = valueFunc(d, i);
- return !isNaN(val) && val !== null;
+ return util.isNonNullFinite(valueFunc(d, i));
},
opacity: m_this.style.get('opacity'),
value: valueFunc

Use the utility function for contour point usage.