@leannedayao it is tough to provide specific guidance around this one without knowing more about what the data outcomes potentially would be that could trigger an error out of the top part of your workflow. Nonetheless, here is one use case for you with Count Records and Message tools to assist.
These are the settings that you would set up in your Message tool (appended below). There is an option to error out the workflow that you could use.
Hoping this inches you closer to finding a solution you're looking for. :)

