workaround for trace disappearing when all transforms are deleted

Author: dmt0

src/EditorControls.js

@@ -232,10 +232,14 @@ class EditorControls extends Component {
           isNumeric(payload.transformIndex) &&
           payload.traceIndex < graphDiv.data.length
         ) {
-          graphDiv.data[payload.traceIndex].transforms.splice(
-            payload.transformIndex,
-            1
-          );
+          if (graphDiv.data[payload.traceIndex].transforms.length === 1) {
+            delete graphDiv.data[payload.traceIndex].transforms;
+          } else {
+            graphDiv.data[payload.traceIndex].transforms.splice(
+              payload.transformIndex,
+              1
+            );
+          }
           if (this.props.onUpdate) {
             this.props.onUpdate(
               graphDiv.data.slice(),

src/components/containers/TransformAccordion.js

@@ -76,7 +76,7 @@ class TransformAccordion extends Component {
           transformIndex={i}
           name={`${
             transformTypes.filter(({type}) => type === tr.type)[0].label
-          }${transformBy[i]}`}
+          }${transformBy && transformBy[i]}`}
           canDelete={true}
         >
           {children}

src/default_panels/GraphTransformsPanel.js

@@ -25,7 +25,10 @@ export class Aggregations extends Component {
     }
 
     return aggregations
-      .filter(aggr => aggr.target.match(/transforms\[\d*\]\./gi) === null)
+      .filter(
+        aggr =>
+          aggr.target && aggr.target.match(/transforms\[\d*\]\./gi) === null
+      )
       .map(({target}, i) => (
         <AggregationSection show key={i} aggregationIndex={i}>
           <Dropdown