subscribers: make creation of routes.js safer.

If by accident this flag is set to true then
build rhodecode from nix wont start because of write failure.

rhodecode/subscribers.py

@@ -241,8 +241,11 b' def write_js_routes_if_enabled(event):'
         jsroutes_file_path = os.path.join(
             static_path, 'js', 'rhodecode', 'routes.js')
 
+        try:
         with io.open(jsroutes_file_path, 'w', encoding='utf-8') as f:
             f.write(jsroutes_file_content)
+        except Exception:
+            log.exception('Failed to write routes.js into %s', jsroutes_file_path)
 
 
 class Subscriber(object):