52404: Undefined variable within the notification payload template

The error indicates that there are one or more undefined variables in the provided template of the notification payload.

1. Missing variables might have been overlooked during template creation.
2. Variables could have been mistyped or not properly declared.

1. Check the debugger logs in the console to identify the exact missing variables.
2. Ensure that all necessary variables are included in either or both of the per-recipient object and the default variables of the notification request.
3. Double-check the spelling and syntax of variables in the template.