FileUploader: no error should be thrown on drag to custom dropZone specified as a string

Author: Zedwag

packages/devextreme/js/__internal/ui/file_uploader.ts

@@ -1747,20 +1747,16 @@ class FileUploader extends Editor<FileUploaderProperties> {
 
   _getDropZoneElement(isCustomTarget: boolean, e: DxEvent): Element | undefined {
     if (!e.currentTarget) {
-      return;
+      return undefined;
     }
 
     const { dropZone } = this.option();
 
-    // @ts-expect-error dropZone option public type: it can be an array of Elements or NodeList
-    const targetList = isCustomTarget ? Array.from(dropZone) : [this._$inputWrapper];
-
-    const targetListElements = targetList.map(
-      (element: dxElementWrapper | string) => $(element).get(0),
-    );
+    const targetList = isCustomTarget ? $(dropZone).toArray() : [this._$inputWrapper];
+    const targetListElements = targetList.map((element) => $(element).get(0));
+    const currentTargetIndex = targetListElements.indexOf(e.currentTarget);
 
-    // eslint-disable-next-line consistent-return
-    return targetListElements[targetListElements.indexOf(e.currentTarget)];
+    return targetListElements[currentTargetIndex];
   }
 
   // eslint-disable-next-line @typescript-eslint/no-invalid-void-type, consistent-return

packages/devextreme/testing/tests/DevExpress.ui.widgets.editors/fileUploader.tests.js

@@ -3901,6 +3901,25 @@ QUnit.module('Drag and drop', moduleConfig, () => {
         assert.notOk(onDropZoneLeaveSpy.called);
     });
 
+    QUnit.test('dropZoneEnter should not cause an error if custom dropZone is specified as string', function(assert) {
+        const customDropZone = $('<div>').addClass('drop').appendTo('#qunit-fixture');
+        const onDropZoneEnterSpy = sinon.spy();
+
+        $('#fileuploader').dxFileUploader({
+            uploadMode: 'useButtons',
+            dropZone: '.drop',
+            onDropZoneEnter: onDropZoneEnterSpy
+        });
+
+        try {
+            triggerDragEvent(customDropZone, 'dragenter');
+
+            assert.ok(true, 'No error is thrown');
+        } catch(error) {
+            assert.ok(false, `Error is thrown: ${error}`);
+        }
+    });
+
     QUnit.test('onValueChanged event should not fire if dragged item is not file', function(assert) {
         const onValueChangedSpy = sinon.spy();