fix coverage for draggable utils

assets/js/utils/__tests__/draggable.spec.ts

@@ -1,4 +1,4 @@
-import { initDraggables } from '../draggable';
+import { clearDragSource, initDraggables } from '../draggable';
 import { fireEvent } from '@testing-library/dom';
 import { getRandomArrayItem } from '../../../test/randomness';
 
@@ -115,6 +115,14 @@ describe('Draggable Utilities', () => {
 
         expect(mockEvent.dataTransfer?.effectAllowed).toEqual('move');
       });
+
+      it('should not throw if the event has no dataTransfer property', () => {
+        initDraggables();
+
+        const mockEvent = createDragEvent('dragstart');
+        delete (mockEvent as Record<keyof typeof mockEvent, unknown>).dataTransfer;
+        expect(() => fireEvent(mockDraggable, mockEvent)).not.toThrow();
+      });
     });
 
     describe('dragOver', () => {
@@ -228,6 +236,20 @@ describe('Draggable Utilities', () => {
           boundingBoxSpy.mockRestore();
         }
       });
+
+      it('should not throw if drag source element is not set', () => {
+        clearDragSource();
+        initDraggables();
+
+        const mockSecondDraggable = createDraggableElement();
+        mockDragContainer.appendChild(mockSecondDraggable);
+
+        const mockDropEvent = createDragEvent('drop');
+        fireEvent(mockDraggable, mockDropEvent);
+
+        expect(() => fireEvent(mockDraggable, mockDropEvent)).not.toThrow();
+        expect(mockDropEvent.defaultPrevented).toBe(true);
+      });
     });
 
     describe('dragEnd', () => {

assets/js/utils/draggable.ts

@@ -53,7 +53,7 @@ function drop(event: DragEvent, target: HTMLElement) {
 }
 
 function dragEnd(event: DragEvent, target: HTMLElement) {
-  dragSrcEl?.classList.remove('dragging');
+  clearDragSource();
 
   if (target.parentNode) {
     $$('.over', target.parentNode).forEach(t => t.classList.remove('over'));
@@ -78,3 +78,11 @@ export function initDraggables() {
   document.addEventListener('dragend', wrapper(dragEnd));
   document.addEventListener('drop', wrapper(drop));
 }
+
+export function clearDragSource() {
+  if (!dragSrcEl) return;
+
+  dragSrcEl.classList.remove('dragging');
+  // eslint-disable-next-line no-undefined
+  dragSrcEl = undefined;
+}