fix(cli(ups-handler), systemd): add type guards and null checks for UPS configs; improve SNMP handling and prompts; guard version display

ts/systemd.ts

@@ -142,11 +142,14 @@ WantedBy=multi-user.target
   private async displayVersionInfo(): Promise<void> {
     try {
       const nupst = this.daemon.getNupstSnmp().getNupst();
+      if (!nupst) {
+        return;
+      }
       const version = nupst.getVersion();
-      
+
       // Check for updates
       const updateAvailable = await nupst.checkForUpdates();
-      
+
       // Display version info
       if (updateAvailable) {
         const updateStatus = nupst.getUpdateStatus();
@@ -161,13 +164,15 @@ WantedBy=multi-user.target
           `${theme.dim('NUPST')} ${theme.dim('v' + version)}  ${symbols.success} ${theme.success('Up to date')}`,
         );
       }
-    } catch (error) {
+    } catch (_error) {
       // If version check fails, show at least the current version
       try {
         const nupst = this.daemon.getNupstSnmp().getNupst();
-        const version = nupst.getVersion();
-        logger.log('');
-        logger.log(`${theme.dim('NUPST')} ${theme.dim('v' + version)}`);
+        if (nupst) {
+          const version = nupst.getVersion();
+          logger.log('');
+          logger.log(`${theme.dim('NUPST')} ${theme.dim('v' + version)}`);
+        }
       } catch (_innerError) {
         // Silently fail if we can't even get the version
       }