添加空值检查防止 undefined 错误

frontend/src/pages/admin/index.vue

@@ -518,7 +518,8 @@ function updateMapOption() {
   if (!chartInstance)
     return
 
-  const data = provinces.value.filter((d: any) => d.count > 0)
+  const provincesData = provinces.value || []
+  const data = provincesData.filter((d: any) => d.count > 0)
   const maxCount = Math.max(...data.map((d: any) => d.count || 0), 1)
 
   const dark = isDark.value
@@ -644,8 +645,9 @@ function initActivityChart() {
         return date.toLocaleDateString('zh-CN', { month: '2-digit', day: '2-digit' })
       })
 
-      const data = onlineTrendData.value.length > 0
-        ? onlineTrendData.value
+      const trendData = onlineTrendData.value || []
+      const data = trendData.length > 0
+        ? trendData
         : Array.from({ length: 30 }).fill(0)
 
       if (activityChartInstance) {