fix(message): support closeBtn="" to render default close icon

[baozjj]

Fixes an inconsistency between Alert and Message components. In Vue, when passing a boolean prop without a value (e.g., <Comp closeBtn />), it is treated as closeBtn="", which is considered truthy. This behavior works in Alert, but not in Message due to use of || when reading props.
Empty string was treated as falsy and caused the logic to fail. Now replaced || with ?? in useTNodeJSX to preserve "".
Also updated the -is-closable class logic in Message to correctly reflect closeBtn="". Open to further suggestions on improving the class condition.

Notably, the following code snippet in useTNodeJSX 89-96:

// If the prop type is a union including Boolean and Function, handle boolean casting as per Vue rules
// https://vuejs.org/guide/components/props.html#boolean-casting
if (types?.length > 1) {
  if (types.includes(Boolean) && types.includes(Function)) {
    if (propsNode === '' && !renderSlot) return defaultNode;
  }
}

reflects an intention to align with Vue's boolean casting behavior.
However, due to the use of || when reading the prop value:

const propsNode = instance.props[camelCase(name)] || instance.props[kebabCase(name)];

the empty string '' is treated as falsy and this intended behavior is not achieved.
Replacing || with ?? fixes this and brings useTNodeJSX in line with Vue's rules.

BREAKING CHANGE: Changed behavior in useTNodeJSX when prop is passed as an empty string. Previously, empty string values (e.g., closeBtn="") were treated as falsy. Now they are preserved and considered as explicitly set, which may affect rendering in some components.

🤔 这个 PR 的性质是？

• 日常 bug 修复
• 新特性提交
• 文档改进
• 演示代码改进
• 组件样式/交互改进
• CI/CD 改进
• 重构
• 代码风格优化
• 测试用例
• 分支合并
• 其他

🔗 相关 Issue

1. 该问题由 Alert 和 Message 组件 closeBtn 行为不一致引起。
2. Vue 中布尔 prop 传入无值时应被视为真值。
3. Message 组件未正确处理该情况，导致关闭按钮无法显示。

💡 需求背景和解决方案

1. Vue 规则说明：在模板中 <Comp closeBtn /> 等价于 closeBtn=""，其应视为真值。
2. Message 组件中 useTNodeJSX 函数中，读取 prop 时使用 || 导致 "" 被视为假值，无法触发关闭按钮渲染。
3. 解决方案是将 || 改为 ??，保持空字符串的显式性。
4. 另外修正 Message 组件关闭按钮 CSS class 逻辑，确保 closeBtn="" 时添加可关闭样式。
5. 保持与 Alert 组件行为一致，避免用户混淆。

• 修复 Message 组件 closeBtn="" 时关闭按钮不显示的问题
• 优化 useTNodeJSX 中 props 读取逻辑，正确处理空字符串值
• 调整 Message 组件关闭按钮样式判断，兼容空字符串值
• 统一 Alert 与 Message 组件的 closeBtn 语义行为
• 添加相关单元测试覆盖

📝 更新日志

tdesign-vue-next

• fix(message): 修复 closeBtn 为空字符串时关闭按钮不显示问题

@tdesign-vue-next/chat

☑️ 请求合并前的自查清单

⚠️ 请自检并全部勾选全部选项。⚠️

• 文档已补充或无须补充
• 代码演示已提供或无须提供
• TypeScript 定义已补充或无须补充
• Changelog 已提供或无须提供

[tdesign-bot]

TDesign Component Site Preview Open

Component	Preview
tdesign-vue-next
@tdesign-vue-next/chat

[pkg-pr-new]

tdesign-vue-next-demo

npm i https://pkg.pr.new/Tencent/tdesign-vue-next@5671

npm i https://pkg.pr.new/Tencent/tdesign-vue-next/@tdesign-vue-next/chat@5671

commit: 3078196