fix: skip an unconfigured go2rtc under the Auto player

With its player left on Auto, a monitor with go2rtc enabled had
selectNextPlayer() pick go2rtc_webrtc first, and with ZM_GO2RTC_PATH
empty select_go2rtc() then alerted "ZM_GO2RTC_PATH is empty", on the
montage for every such monitor, although nobody had chosen go2rtc.

The fallback chain already skipped go2rtc for a monitor without it
enabled; skip it when ZM_GO2RTC_PATH is empty too. A monitor or browser
that chose go2rtc reaches select_go2rtc() directly and still gets the
alert.

A node test drives selectPlayer() through the restart chain for Auto
without a path, Auto with one, and go2rtc chosen explicitly.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/js/monitorstream-go2rtc-auto.test.js

@@ -0,0 +1,121 @@
+'use strict';
+
+// A monitor with go2rtc enabled and its player left on Auto tried go2rtc first,
+// and with ZM_GO2RTC_PATH empty select_go2rtc() alerted "ZM_GO2RTC_PATH is empty"
+// on every page that showed it, montage included, although nobody had asked for
+// go2rtc. Under Auto an unconfigured go2rtc is now skipped for the next player;
+// the alert stays for a monitor or browser that chose go2rtc explicitly.
+
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const vm = require('vm');
+
+const src = fs.readFileSync(
+    path.join(__dirname, '../../web/js/MonitorStream.js'), 'utf8');
+
+let passed = 0;
+let failed = 0;
+function test(name, fn) {
+  try {
+    fn();
+    console.log('  ok ' + name);
+    passed++;
+  } catch (e) {
+    console.error('  FAIL ' + name);
+    console.error('    ' + (e.stack || e.message));
+    failed++;
+  }
+}
+
+function makeChainable() {
+  const proxy = new Proxy(function() {}, {
+    get: (target, prop) => (prop === 'then' ? undefined : proxy),
+    apply: () => proxy,
+  });
+  return proxy;
+}
+
+function loadMonitorStream(go2rtcPath) {
+  const globals = {
+    ZM_GO2RTC_PATH: go2rtcPath,
+    parseInt, Number, Object, Math, String, Array, JSON,
+    alerts: [],
+    alert(msg) {
+      this.alerts.push(msg);
+    },
+    $j: makeChainable(),
+    $: makeChainable(),
+    console: {log() {}, warn() {}, error() {}, debug() {}},
+    currentView: 'watch',
+    getCookie: () => 'true',
+    setCookie: () => {},
+    document: {
+      getElementById: () => null,
+      querySelector: () => null,
+      createElement: () => ({}),
+    },
+    setTimeout: () => 0,
+    clearTimeout: () => 0,
+    setInterval: () => 0,
+    clearInterval: () => 0,
+  };
+  const sandbox = new Proxy(globals, {
+    has: () => true, // make every bare identifier resolve against this object
+    get: (target, prop) => (prop === Symbol.unscopables ? undefined : target[prop]),
+  });
+  globals.window = sandbox;
+  vm.createContext(sandbox);
+  vm.runInContext(src, sandbox, {filename: 'MonitorStream.js'});
+  assert.strictEqual(typeof globals.MonitorStream, 'function',
+      'MonitorStream.js did not define MonitorStream');
+  return globals;
+}
+
+
+// Build a go2rtc-enabled monitor and record which player selectPlayer() starts.
+function select(go2rtcPath, defaultPlayer) {
+  const sandbox = loadMonitorStream(go2rtcPath);
+  const monitor = new sandbox.MonitorStream({
+    id: 2, name: 'test', connKey: null, url: '', url_to_zms: '',
+    width: 640, height: 480, Go2RTCEnabled: true, DefaultPlayer: defaultPlayer,
+  });
+  const started = [];
+  monitor.isActive = true;
+  monitor.select_go2rtc = () => started.push('go2rtc');
+  monitor.select_janus = () => started.push('janus');
+  monitor.select_rtsp2web = () => started.push('rtsp2web');
+  monitor.select_zms = () => started.push('zms');
+  // selectNextPlayer() switches by setting this.player and restarting, and
+  // restart() comes back through selectPlayer() with the new player.
+  let depth = 0;
+  monitor.restart = () => {
+    started.push('restart:' + monitor.player);
+    if (++depth < 10) monitor.selectPlayer('default');
+  };
+  monitor.selectPlayer('default');
+  return {started, alerts: sandbox.alerts};
+}
+
+console.log('MonitorStream player selection with go2rtc unconfigured');
+
+test('Auto with no ZM_GO2RTC_PATH does not try go2rtc or alert', () => {
+  const {started, alerts} = select('', '');
+  assert.ok(!started.includes('go2rtc'), 'started go2rtc: ' + started.join(','));
+  assert.deepStrictEqual(alerts, []);
+  assert.ok(started.includes('zms'), 'did not fall back to zms: ' + started.join(','));
+});
+
+test('go2rtc chosen for the monitor still tries go2rtc', () => {
+  const {started} = select('', 'go2rtc');
+  assert.deepStrictEqual(started, ['go2rtc']);
+});
+
+test('Auto with ZM_GO2RTC_PATH set uses go2rtc', () => {
+  const {started, alerts} = select('http://localhost:1984', '');
+  assert.ok(started.includes('go2rtc'), 'did not start go2rtc: ' + started.join(','));
+  assert.deepStrictEqual(alerts, []);
+});
+
+console.log('\n' + passed + ' passed, ' + failed + ' failed');
+process.exit(failed ? 1 : 0);

web/js/MonitorStream.js

@@ -2319,7 +2319,10 @@ function MonitorStream(monitorData) {
         while (idx !== -1 && idx + 1 < keys.length) {
           const nextKey = keys[++idx];
           const nextName = this.playerPriority[nextKey]['name'];
-          if (nextName.indexOf('go2rtc') !== -1 && !this.Go2RTCEnabled) continue;
+          // Skip an unconfigured go2rtc here rather than letting select_go2rtc() alert:
+          // this is the Auto path, so nobody chose go2rtc. A monitor or browser that
+          // did choose it reaches select_go2rtc() directly and still gets the alert.
+          if (nextName.indexOf('go2rtc') !== -1 && (!this.Go2RTCEnabled || !ZM_GO2RTC_PATH)) continue;
           if (nextName.indexOf('rtsp2web') !== -1 && !this.RTSP2WebEnabled) continue;
           if (nextName.indexOf('janus') !== -1 && !this.janusEnabled) continue;
           if (this.selectedPlayer === 'go2rtc' && nextName.indexOf('go2rtc') === -1 && nextName.indexOf('zms') === -1 ) continue;