Fix crash connecting to node with no slots (#644)

* Fix crash connecting to node with no slots

* Add playwright test

* Update test expectations [skip ci]

---------

Co-authored-by: huchenlei <chenlei.hu@mail.utoronto.ca>
Co-authored-by: github-actions <github-actions@github.com>

browser_tests/nodeSearchBox.spec.ts

@@ -65,4 +65,16 @@ test.describe('Node search box', () => {
       'auto-linked-node-batch.png'
     )
   })
+
+  test('Link release connecting to node with no slots', async ({
+    comfyPage
+  }) => {
+    await comfyPage.disconnectEdge()
+    await expect(comfyPage.searchBox.input).toHaveCount(1)
+    await comfyPage.page.locator('.p-chip-remove-icon').click()
+    await comfyPage.searchBox.fillAndSelectFirstNode('KSampler')
+    await expect(comfyPage.canvas).toHaveScreenshot(
+      'added-node-no-connection.png'
+    )
+  })
 })