Fix/handle missing src dst in traffic entries (#127)

* fix: guard against undefined src/dst in traffic entries

Some exitTraffic entries from the Tailscale API omit the src field,
causing a TypeError (Cannot read properties of undefined reading
'startsWith') in isIPAddress() which crashes the entire data loading
pipeline.

Changes:
- Add null guard to isIPAddress() to return false for falsy input
- Skip traffic entries with missing src or dst in processNetworkLogs()
- Add null guards to extractIP() and extractPort() in ip-utils.ts

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: guard against null IP values

* fix: add comment about fix to guard against null values

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: cmmattson

frontend/src/lib/utils/ip-utils.ts

@@ -1,5 +1,7 @@
 // Extract IP from address (remove port if present)
 export function extractIP(address: string): string {
+	//Guard Against Null Values
+	if (!address) return '';
 	// Handle IPv6 addresses like [fd7a:115c:a1e0::9001:b818]:62574
 	if (address.startsWith('[') && address.includes(']:')) {
 		return address.substring(1, address.indexOf(']:'));
@@ -20,6 +22,8 @@ export function extractIP(address: string): string {
 
 // Extract port from address:port string
 export function extractPort(address: string): number | null {
+	//Guard Against Null Values
+	if (!address) return null;
 	// Handle IPv6 addresses like [fd7a:115c:a1e0::9001:b818]:62574
 	if (address.startsWith('[') && address.includes(']:')) {
 		const portStr = address.split(']:')[1];
@@ -45,6 +49,9 @@ export function extractPort(address: string): number | null {
 
 // Categorize IP addresses by type
 export function categorizeIP(ip: string): string[] {
+	//Guard Against Null Values
+	if (!ip) return ['null'];
+	
 	// DERP servers
 	if (ip === '127.3.3.40') return ['derp'];
 

frontend/src/lib/utils/network-processor.ts

@@ -20,6 +20,8 @@ interface ProcessedNetwork {
 
 // Check if a string looks like an IP address (vs a device ID)
 function isIPAddress(value: string): boolean {
+	//Guard against null values
+	if (!value) return false;
 	// IPv4: contains dots and numbers
 	if (/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(:\d+)?$/.test(value)) return true;
 	// IPv6: contains colons but starts with [ or has many colons
@@ -144,6 +146,10 @@ export function processNetworkLogs(
 		];
 
 		allTraffic.forEach((traffic) => {
+			// Skip entries with missing src or dst (e.g. some exitTraffic entries
+			// from the Tailscale API omit the src field)
+			if (!traffic.src || !traffic.dst) return;
+
 			// Handle both IP:port format (live) and device ID format (historical)
 			const srcIP = resolveToIP(traffic.src, devices);
 			const dstIP = resolveToIP(traffic.dst, devices);