🐛 fix(vscode): GitHub 工单已被删除（410）时按不存在处理，不再报错

vscode/src/forge/github/provider.test.ts

@@ -148,6 +148,11 @@ describe('工单', () => {
     expect(await p.getIssue(9)).toBeNull()
   })
 
+  it('工单已被删除（410）也返回 null', async () => {
+    stubFetch(new Response('{"message":"This issue was deleted"}', { status: 410 }))
+    expect(await provider().getIssue(5)).toBeNull()
+  })
+
   it('其它失败照常抛 ForgeApiError', async () => {
     stubFetch(new Response('boom', { status: 500 }))
     await expect(provider().getIssue(1)).rejects.toBeInstanceOf(ForgeApiError)