fix: avoid mutating original server array and add null guard

Address code review findings:
- Sort a shallow copy instead of mutating the caller's array
- Add null guard on server.name to handle malformed entries
- Use original SPEEDTEST_SERVERS index for classic UI option values

frontend/javascript/index.js

@@ -231,18 +231,20 @@ function populateDropdown(servers) {
   }
 
   // Sort servers by country, then by city within the same country
-  servers.sort((a, b) => {
-    const commaA = a.name.lastIndexOf(",");
-    const commaB = b.name.lastIndexOf(",");
-    const countryA = commaA >= 0 ? a.name.substring(commaA + 1).trim() : a.name;
-    const countryB = commaB >= 0 ? b.name.substring(commaB + 1).trim() : b.name;
-    const cityA = commaA >= 0 ? a.name.substring(0, commaA).trim() : "";
-    const cityB = commaB >= 0 ? b.name.substring(0, commaB).trim() : "";
+  const sorted = [...servers].sort((a, b) => {
+    const nameA = a.name || "";
+    const nameB = b.name || "";
+    const commaA = nameA.lastIndexOf(",");
+    const commaB = nameB.lastIndexOf(",");
+    const countryA = commaA >= 0 ? nameA.substring(commaA + 1).trim() : nameA;
+    const countryB = commaB >= 0 ? nameB.substring(commaB + 1).trim() : nameB;
+    const cityA = commaA >= 0 ? nameA.substring(0, commaA).trim() : "";
+    const cityB = commaB >= 0 ? nameB.substring(0, commaB).trim() : "";
     return countryA.localeCompare(countryB) || cityA.localeCompare(cityB);
   });
 
   // Populate the list to choose from
-  servers.forEach((server) => {
+  sorted.forEach((server) => {
     const item = document.createElement("li");
     const link = document.createElement("a");
     link.href = "#";

index-classic.html

@@ -51,22 +51,24 @@
 						if (server != null) { //at least 1 server is available
 							I("loading").className = "hidden"; //hide loading message
 							//sort servers by country, then by city
-							SPEEDTEST_SERVERS.sort(function (a, b) {
-								var commaA = a.name.lastIndexOf(",");
-								var commaB = b.name.lastIndexOf(",");
-								var countryA = commaA >= 0 ? a.name.substring(commaA + 1).trim() : a.name;
-								var countryB = commaB >= 0 ? b.name.substring(commaB + 1).trim() : b.name;
-								var cityA = commaA >= 0 ? a.name.substring(0, commaA).trim() : "";
-								var cityB = commaB >= 0 ? b.name.substring(0, commaB).trim() : "";
+							var sortedServers = SPEEDTEST_SERVERS.slice().sort(function (a, b) {
+								var nameA = a.name || "";
+								var nameB = b.name || "";
+								var commaA = nameA.lastIndexOf(",");
+								var commaB = nameB.lastIndexOf(",");
+								var countryA = commaA >= 0 ? nameA.substring(commaA + 1).trim() : nameA;
+								var countryB = commaB >= 0 ? nameB.substring(commaB + 1).trim() : nameB;
+								var cityA = commaA >= 0 ? nameA.substring(0, commaA).trim() : "";
+								var cityB = commaB >= 0 ? nameB.substring(0, commaB).trim() : "";
 								return countryA.localeCompare(countryB) || cityA.localeCompare(cityB);
 							});
 							//populate server list for manual selection
-							for (var i = 0; i < SPEEDTEST_SERVERS.length; i++) {
-								if (SPEEDTEST_SERVERS[i].pingT == -1) continue;
+							for (var i = 0; i < sortedServers.length; i++) {
+								if (sortedServers[i].pingT == -1) continue;
 								var option = document.createElement("option");
-								option.value = i;
-								option.textContent = SPEEDTEST_SERVERS[i].name;
-								if (SPEEDTEST_SERVERS[i] === server) option.selected = true;
+								option.value = SPEEDTEST_SERVERS.indexOf(sortedServers[i]);
+								option.textContent = sortedServers[i].name;
+								if (sortedServers[i] === server) option.selected = true;
 								I("server").appendChild(option);
 							}
 							//show test UI