Function application_error_headers

pub fn application_error_headers(
    custom_user_data: &Vec<(String, String)>,
) -> (Option<String>, Option<String>)

Helper function to return the application error code and payload, if present in custom_user_data.

Returns a [(Option<String>, Option<String>)] tuple where:

• the first element is the application error code (or None if not present), and
• the second element is the application error payload (or None if not present).