fix: restore default node correctly when using helperText (#7449)

Author: web-padawan

packages/component-base/src/slot-controller.js

@@ -111,12 +111,12 @@ export class SlotController extends EventTarget {
         if (slotName !== '') {
           node.setAttribute('slot', slotName);
         }
-        this.node = node;
         this.defaultNode = node;
       }
     }
 
     if (node) {
+      this.node = node;
       host.appendChild(node);
     }
 

packages/field-base/test/field-mixin.test.js

@@ -592,6 +592,17 @@ const runTests = (defineHelper, baseMixin) => {
           expect(element._helperNode).to.equal(defaultHelper);
         });
 
+        it('should restore the default helper when restoring helperText immediately', async () => {
+          element.helperText = null;
+          element.appendChild(helper);
+          await nextRender();
+
+          element.removeChild(helper);
+          element.helperText = 'Updated helper';
+          await nextRender();
+          expect(element._helperNode.textContent).to.equal('Updated helper');
+        });
+
         it('should keep has-helper attribute when the default helper is restored', async () => {
           element.appendChild(helper);
           await nextRender();