judge: distinguish sandbox error between old version and not running (#813)

packages/hydrojudge/src/sandbox.ts

@@ -230,7 +230,8 @@ export async function versionCheck(reportWarn: (str: string) => void, reportErro
         const config = await client.config();
         sandboxCgroup = config.runnerConfig?.cgroupType || 0;
     } catch (e) {
-        reportError('Your sandbox version is tooooooo low! Please upgrade!');
+        if (e?.syscall === 'connect') reportError('Connecting to sandbox failed, please check sandbox_host config and if your sandbox is running.');
+        else reportError('Your sandbox version is tooooooo low! Please upgrade!');
         return false;
     }
     const { osinfo } = await sysinfo.get();