We have a huge application that very often outputs errors like:
Argument "" isn't numeric in gt (>) at input text line xxx, <GENyyy> line zzz and of course we want to fix them.

But look for example to a line from the logs:

Argument "arbeitet sorgfältig, konzentriert und zuverlässig" isn't numeric in numeric comparison (<=>) at /usr/lib64/perl5/vendor_perl/Template/VMethods.pm line 559, <GEN20> line 4.

or a shorter version without VMethods:

Argument "" isn't numeric in numeric gt (>) at input text line 71, <GEN226> line 4.

The problem especially with the second one is that we have absolutely no clue where to look for it and fix it but it produces thousands of logs entries a day. But what is even? I haven’t found any information on the web what it maeans.

So how do I interpret this and how to get more information where this exactly happens. I had one idea of installing a $SIG{___WARN___} handler and print a callstack but it would probably kill the webapp as it would emit thousands of signals then and clutter the logs with callstacks.

Does anybody have a clever idea on how to track down those errors?

Normally perl prints the file & line where this error happens but here it just emits some increasing number and with various line numbers. So I guess it’s different places where it occurs but without further information I can’t debug it.