Best practice for completeness checks when using join

Hi all,

I wanted to ask what the best practice is for handling Joiner node outputs, specifically in terms of not losing any data.

Example scenario:

1. The main workflow is connected to a second table via Joiner. The second table is a shared Excel sheet that may be modified over time.

2. I need to ensure that the Excel sheet contains all the keys from the main workflow and that no data from the main workflow remains unmatched.

I can check this manually by outputting Left unmatched rows and manually checking if the table is empty (as it should be). However, if the workflow is sufficiently large, it becomes unpractical to check each node manually.

Is there any kind of error reporting system that I can use for this? I know that Alteryx has a Test node that can error the entire workflow if the number of rows in a specified output table is not zero. Would there be anything similar to this in KNIME?

(I tried the Breakpoint node, but it only seems to work for tables that are empty, as opposed to tables that are not empty.)

Thank you in advance and greatly appreciate any advice.