fix: missing navigator object in server-side

packages/frontend/src/components/VDFtester.svelte

@@ -2,10 +2,9 @@
 	import {N_ARRAY} from "src/const";
 	import {fade} from "svelte/transition";
 	import {UAParser} from 'ua-parser-js';
+	import {onMount} from "svelte";
 
-    const ua = navigator ? navigator.userAgent : "";
-
-    const { browser } = UAParser(ua);
+	let browserInfo: null | string = null;
 
 	let bigintSupported = typeof BigInt !== 'undefined';
 
@@ -163,6 +162,12 @@
 		}
 		return Number(speedSample.difficulty) / speedSample.time * 1000;
 	}
+
+	onMount(() => {
+		const ua = navigator ? navigator.userAgent : "";
+		const {browser} = UAParser(ua);
+		browserInfo = browser.name + " " + browser.version;
+	})
 </script>
 
 <div
@@ -216,7 +221,9 @@
 				速度是在 N = {speedSample.N.toString(2).length} bits, T = {speedSample.difficulty} 的测试中测量的.
 			</span>
 			<br/>
-            浏览器版本：{browser}
+			{#if browserInfo}
+				浏览器版本：{browserInfo}
+			{/if}
 		</p>
 		<table class="w-full text-sm text-left rtl:text-right mt-4">
 			<thead class="text-sm uppercase font-medium border-b border-outline dark:border-dark-outline">