Does Bash have an option to diagnose "expanded to empty value" variables? [duplicate]

Question

Does Bash have an option to diagnose (and optionally abort execution) "expanded to empty value" variables?

Example (hypothetical):

$ bash -c 'echo $x' --xxx
bash: line 1: variable 'x' expanded to empty value

Reason for the question: such an option may be useful when debugging scripts.

For example, in some script all variables are expected to expand to a non-empty values. Hence, using an option to detect (and optionally abort execution) "expanded to empty value" variables may be useful for such case.

I've already searched for this option in set builtin, but have found nothing.

Answer 1

All sh shells can make accessing unset variables an error, by running

set -u

The error causes the shell to exit with a non-zero status. When the error occurs in a subshell, only that subshell exits, and it's up to the calling code to propagate the error if it wants to.

Example:

$ bash -c 'echo hello $x world; echo continuing'
hello world
continuing
$ bash -c 'set -u; echo hello $x world; echo continuing'
bash: line 1: x: unbound variable
$ bash -u -c 'echo hello $x world; echo continuing'
bash: line 1: x: unbound variable

I don't think there's any way to apply this to variables that are set to an empty value. That is a weird requirement. What's special about the empty string that makes it less good than any non-empty string?

$ bash -c 'set -u; x=$(true); echo "x ($x) is empty, so what?"'
x () is empty, so what?