Toolkit Template to throw error when encounter undefined variable

Question

I am using Linux tpage 2.7 (Template Toolkit version 2.27) with a bunch of template files. All variables are passed to tpage via command line as --define var=value. I would like tpage to throw some kind of error if variable exists in the template, but is not passed a definition via the command line. The tpage --help states the following in options:

--debug=STRING           Set TT DEBUG option to STRING

It is not clear what should be placed instead of STRING. I found a manual and for my version the debug flag is DEBUG_UNDEF, but when I pass this option to tpage via command line like --debug=DEBUG_UNDEF, I get an error:

unknown debug flag: DEBUG_UNDEF

A similar question is here, but the answer does not provide a solution how to pass this switch option via the command line.

Q1: Is there any way to enable undefined exception via command line?

Q2: I want empty string like --define myName="" not to be considered as undefined.

Answer 1

Looks like the format option worked for me:

--debug="undef"