fix(c3-chart): stop donutPctCharts without a threshold attribute from regenerating when updating data

Author: aptmac

src/charts/c3/c3-chart.component.js

@@ -97,9 +97,9 @@
           chartData = ctrl.config;
           if (chartData) {
             chartData.bindto = '#' + $attrs.id;
-            // always re-generate donut pct chart because it's colors
-            // change based on data and thresholds
-            if (!chart || $attrs.id.includes('donutPctChart')) {
+            // only re-generate donut pct chart if it has a threshold object
+            // because it's colors will change based on data and thresholds
+            if (!chart || ($attrs.id.includes('donutPctChart') && chartData.thresholds)) {
               chart = c3.generate(chartData);
             } else {
               //if chart is already created, then we only need to re-load data