Use function to create new trace

Author: VeraZab

src/EditorControls.js

@@ -122,9 +122,7 @@ class EditorControls extends Component {
         // can't use default prop because plotly.js mutates it:
         // https://github.com/plotly/react-chart-editor/issues/509
         graphDiv.data.push(
-          this.props.useAsDefaultTrace
-            ? this.props.useAsDefaultTrace
-            : {type: 'scatter', mode: 'markers'}
+          this.props.makeDefaultTrace(this.props.useAsDefaultTrace)
         );
 
         if (this.props.afterAddTrace) {
@@ -307,11 +305,18 @@ EditorControls.propTypes = {
   showFieldTooltips: PropTypes.bool,
   traceTypesConfig: PropTypes.object,
   useAsDefaultTrace: PropTypes.object,
+  makeDefaultTrace: PropTypes.func,
 };
 
 EditorControls.defaultProps = {
   showFieldTooltips: false,
   locale: 'en',
+  makeDefaultTrace: suppliedDefault => {
+    if (suppliedDefault) {
+      return suppliedDefault;
+    }
+    return {type: 'scatter', mode: 'markers'};
+  },
   traceTypesConfig: {
     categories: _ => categoryLayout(_),
     traces: _ => traceTypes(_),