Merge another table-Lookup warning if not found?

When using Merge another table-Lookup, is there a way to have EasyMorph generate a warning if a lookup value is not found in the lookup table? I believe it does so if no matches are found, but I would like to detect if any single value is not found.

The Merge action actually does generate a warning if appended columns contain no data. The "Lookup" action doesn't, as far as I remember.

Alternatively, you can add the "Halt/warn on condition" action in the "Warning" mode with the condition

   isempty([Column])" 

for every value in [Column].

In the "Warning" mode, the action generates a warning.

Yes, I had thought of adding a Halt/warn on condition action, however I am sometimes doing 15-20 merges and adding an additional Halt/warn for each one of them is making the project a bit unwieldly.

I believe I will have to find another approach. Thank you!