feat(dashboard): Add error handling to serveMetrics method for improved resilience

ts_web_serviceworker/classes.dashboard.ts

@@ -34,48 +34,78 @@ export class DashboardGenerator {
    * - Resource data
    */
   public async serveMetrics(): Promise<Response> {
-    const metrics = getMetricsCollector();
-    const persistentStore = getPersistentStore();
-    await persistentStore.init();
-    const requestLogStore = getRequestLogStore();
+    try {
+      const metrics = getMetricsCollector();
+      const persistentStore = getPersistentStore();
+      await persistentStore.init();
+      const requestLogStore = getRequestLogStore();
 
-    // Get event data
-    const eventResult = await persistentStore.getEventLog({ limit: 50 });
-    const oneHourAgo = Date.now() - 3600000;
-    const eventCountLastHour = await persistentStore.getEventCount(oneHourAgo);
+      // Get event data
+      const eventResult = await persistentStore.getEventLog({ limit: 50 });
+      const oneHourAgo = Date.now() - 3600000;
+      const eventCountLastHour = await persistentStore.getEventCount(oneHourAgo);
 
-    // Build comprehensive initial response
-    const data = {
-      // Core metrics
-      ...metrics.getMetrics(),
-      cacheHitRate: metrics.getCacheHitRate(),
-      networkSuccessRate: metrics.getNetworkSuccessRate(),
-      resourceCount: metrics.getResourceCount(),
-      summary: metrics.getSummary(),
+      // Build comprehensive initial response
+      const data = {
+        // Core metrics
+        ...metrics.getMetrics(),
+        cacheHitRate: metrics.getCacheHitRate(),
+        networkSuccessRate: metrics.getNetworkSuccessRate(),
+        resourceCount: metrics.getResourceCount(),
+        summary: metrics.getSummary(),
 
-      // Resources data
-      resources: metrics.getCachedResources(),
-      domains: metrics.getDomainStats(),
-      contentTypes: metrics.getContentTypeStats(),
+        // Resources data
+        resources: metrics.getCachedResources(),
+        domains: metrics.getDomainStats(),
+        contentTypes: metrics.getContentTypeStats(),
 
-      // Events data (initial 50)
-      events: eventResult.events,
-      eventTotalCount: eventResult.totalCount,
-      eventCountLastHour,
+        // Events data (initial 50)
+        events: eventResult.events,
+        eventTotalCount: eventResult.totalCount,
+        eventCountLastHour,
 
-      // Request logs data (initial 50)
-      requestLogs: requestLogStore.getEntries({ limit: 50 }),
-      requestTotalCount: requestLogStore.getTotalCount(),
-      requestStats: requestLogStore.getStats(),
-      requestMethods: requestLogStore.getMethods(),
-    };
+        // Request logs data (initial 50)
+        requestLogs: requestLogStore.getEntries({ limit: 50 }),
+        requestTotalCount: requestLogStore.getTotalCount(),
+        requestStats: requestLogStore.getStats(),
+        requestMethods: requestLogStore.getMethods(),
+      };
 
-    return new Response(JSON.stringify(data), {
-      headers: {
-        'Content-Type': 'application/json',
-        'Cache-Control': 'no-store',
-      },
-    });
+      return new Response(JSON.stringify(data), {
+        headers: {
+          'Content-Type': 'application/json',
+          'Cache-Control': 'no-store',
+        },
+      });
+    } catch (error) {
+      console.error('[SW Dashboard] serveMetrics error:', error);
+      // Return error response with valid JSON structure so client doesn't crash
+      return new Response(JSON.stringify({
+        error: String(error),
+        cache: { hits: 0, misses: 0, errors: 0, bytesServedFromCache: 0, bytesFetched: 0, averageResponseTime: 0 },
+        network: { totalRequests: 0, successfulRequests: 0, failedRequests: 0, timeouts: 0, averageLatency: 0, totalBytesTransferred: 0 },
+        update: { totalChecks: 0, successfulChecks: 0, failedChecks: 0, updatesFound: 0, updatesApplied: 0, lastCheckTimestamp: 0, lastUpdateTimestamp: 0 },
+        connection: { connectedClients: 0, totalConnectionAttempts: 0, successfulConnections: 0, failedConnections: 0 },
+        speedtest: { lastDownloadSpeedMbps: 0, lastUploadSpeedMbps: 0, lastLatencyMs: 0, lastTestTimestamp: 0, testCount: 0, isOnline: false },
+        startTime: Date.now(),
+        uptime: 0,
+        cacheHitRate: 0,
+        networkSuccessRate: 0,
+        resourceCount: 0,
+        events: [],
+        eventTotalCount: 0,
+        eventCountLastHour: 0,
+        requestLogs: [],
+        requestTotalCount: 0,
+        requestStats: { totalRequests: 0, totalResponses: 0, methodCounts: {}, errorCount: 0, avgDurationMs: 0 },
+        requestMethods: [],
+      }), {
+        headers: {
+          'Content-Type': 'application/json',
+          'Cache-Control': 'no-store',
+        },
+      });
+    }
   }
 
   /**