fix(plugin-server-session): delay initialization until first use (#2642)

* fix(plugin-server-session): delay session tracker initialization until first use

* docs(plugin-server-session): add changelog entry

Author: hamudi-ahmed

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+(plugin-server-session) Delay session tracker initialization until first use [#2642](https://github.com/bugsnag/bugsnag-js/pull/2642)
+
 ### Dependencies
 
 Update bugsnag-cocoa to [6.34.1](https//github.com/bugsnag/bugsnag-cocoa/releases/tag/6.34.1) [#2606](https://github.com/bugsnag/bugsnag-js/pull/2606)

packages/plugin-server-session/session.js

@@ -5,11 +5,17 @@ const runSyncCallbacks = require('@bugsnag/core/lib/sync-callback-runner')
 
 module.exports = {
   load: (client) => {
-    const sessionTracker = new SessionTracker(client._config.sessionSummaryInterval)
-    sessionTracker.on('summary', sendSessionSummary(client))
-    sessionTracker.start()
+    let sessionTracker = null
+
     client._sessionDelegate = {
       startSession: (client, session) => {
+        // Lazy initialization: only create and start the tracker on first use
+        if (!sessionTracker) {
+          sessionTracker = new SessionTracker(client._config.sessionSummaryInterval)
+          sessionTracker.on('summary', sendSessionSummary(client))
+          sessionTracker.start()
+        }
+
         client._session = session
         client._pausedSession = null
         sessionTracker.track(client._session)