Bugfix/undefined time zone in auth interceptor (#8181)

* Fix exception when time zone of browser unavailable

* Update changelog

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Hardened the validation of the date in the endpoint to create an account balance
 - Upgraded `bootstrap` from version `4.6.2` to `5.3.8`
 
+### Fixed
+
+- Fixed an exception in the authentication interceptor when the time zone of the browser is not available
+
 ## 3.86.0 - 2026-10-13
 
 ### Added

apps/client/src/app/core/auth.interceptor.ts

@@ -38,10 +38,13 @@ export class AuthInterceptor implements HttpInterceptor {
       return next.handle(request);
     }
 
-    let headers = request.headers.set(
-      HEADER_KEY_TIMEZONE,
-      Intl?.DateTimeFormat().resolvedOptions().timeZone
-    );
+    let headers = request.headers;
+
+    const timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;
+
+    if (timezone) {
+      headers = headers.set(HEADER_KEY_TIMEZONE, timezone);
+    }
 
     const token = this.tokenStorageService.getToken();