fix: 修复 schema 切换时 generator 被旧 config 调用导致白板

根因: activeSchemaId 变化后，ConfigForm 还没 emit 新默认值，generator 就用旧 config 执行了
修复: 在 App.vue 中 watch activeSchemaId，切换时立即用新 schema 默认值重置 config
同时修复 bind.js 中 forwarders.split() 的防御性空值处理

src/App.vue

@@ -15,7 +15,7 @@
 </template>
 
 <script setup>
-import { ref, computed } from 'vue'
+import { ref, computed, watch } from 'vue'
 import Sidebar from './components/Sidebar.vue'
 import ConfigForm from './components/ConfigForm.vue'
 import CodePreview from './components/CodePreview.vue'
@@ -26,6 +26,11 @@ const currentConfig = ref({})
 
 const currentSchema = computed(() => schemas[activeSchemaId.value])
 
+// 当 schema 切换时，立即用新 schema 的默认值重置 config
+watch(activeSchemaId, (newId) => {
+  currentConfig.value = getDefaultValues(schemas[newId])
+})
+
 const generatedCode = computed(() => {
   const gen = generators[activeSchemaId.value]
   if (!gen) return ''

src/main.js

@@ -5,6 +5,11 @@ import * as ElementPlusIconsVue from '@element-plus/icons-vue'
 import App from './App.vue'
 
 const app = createApp(App)
+
+app.config.errorHandler = (err, instance, info) => {
+  console.error('Vue Error:', err, info)
+}
+
 app.use(ElementPlus, { size: 'default' })
 
 for (const [key, component] of Object.entries(ElementPlusIconsVue)) {

src/schemas/bind.js

@@ -174,7 +174,7 @@ export function generateBindConf(config) {
   lines.push(`  recursion ${config.recursion ? 'yes' : 'no'};`)
   lines.push(``)
   lines.push(`  forwarders {`)
-  const forwarders = config.forwarders.split(';').map((s) => s.trim()).filter(Boolean)
+  const forwarders = (config.forwarders || '').split(';').map((s) => s.trim()).filter(Boolean)
   forwarders.forEach((f) => {
     lines.push(`    ${f};`)
   })