Fix bug with pie/doughnut chart legends

Fixes a rendering issue when there are multiple datasets on a pie chart and they do not all contain the same number of data in their datasets
Fixes #3309

diff --git a/src/controllers/controller.doughnut.js b/src/controllers/controller.doughnut.js
index 0e9c5fe802cce90bd8774011b4adcd385a49c9b5..e0f378daed55c781a4d5ff2dedd25e1c7dce70bc 100644 (file)
--- a/src/controllers/controller.doughnut.js
+++ b/src/controllers/controller.doughnut.js
@@ -76,7 +76,10 @@ module.exports = function(Chart) {
 
                                for (i = 0, ilen = (chart.data.datasets || []).length; i < ilen; ++i) {
                                        meta = chart.getDatasetMeta(i);
-                                       meta.data[index].hidden = !meta.data[index].hidden;
+                                       // toggle visibility of index if exists
+                                       if (meta.data[index]) {
+                                               meta.data[index].hidden = !meta.data[index].hidden;
+                                       }
                                }
 
                                chart.update();