Merge branch 'MonoidMusician-patch-1'

mauriciopoppe · Jul 15, 2017 · 3b2ad9e · 3b2ad9e
2 parents 1f18f73 + adf4e69
commit 3b2ad9e
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/lib/helpers/derivative.js b/lib/helpers/derivative.js
@@ -41,7 +41,9 @@ module.exports = function (chart) {
       d.derivative.$$mouseListener = function (x0) {
         // update initial value to be the position of the mouse
         // scope's x0 will be updated on the next call to `derivative(self)`
-        d.derivative.x0 = x0
+        if (d.derivative) {
+          d.derivative.x0 = x0
+        }
         // trigger update (selection = self)
         derivative(self)
       }