feat: add action row for challenges with ERMs on desktop (#39377)

client/src/templates/Challenges/utils/getTargetEditor.js

@@ -0,0 +1,14 @@
+import { toSortedArray } from '../../../../../utils/sort-files';
+import { isEmpty } from 'lodash';
+
+export function getTargetEditor(challengeFiles) {
+  if (isEmpty(challengeFiles)) return null;
+  else {
+    let targetEditor = Object.values(challengeFiles).find(
+      ({ editableRegionBoundaries }) => !isEmpty(editableRegionBoundaries)
+    )?.key;
+
+    // fallback for when there is no editable region.
+    return targetEditor || toSortedArray(challengeFiles)[0].key;
+  }
+}