When evaluating the variable testing condition, it should stop as soon as there's an error evaluating a variable. Instead, at the moment, it then tries to evaluate the testing condition and shows the error produced by that, typically "<variable name> is not defined".
Here's a minimal example: https://numbas.mathcentre.ac.uk/question/share/view/398938e6-f8fe-4069-a21e-59ed3889eb8f
When evaluating the variable testing condition, it should stop as soon as there's an error evaluating a variable. Instead, at the moment, it then tries to evaluate the testing condition and shows the error produced by that, typically "
<variable name>is not defined".