fix(bash-v2): activeHelp length check syntax

[scop]

$ set -u
$ foo=()
$ echo ${#foo}
bash: foo: unbound variable
echo ${#foo[*]}
0

[scop]

#1702 requires a rebase after this is in, will take care of it.

[marckhouzam]

Nice catch! Thanks @scop. I'll run some tests on this next week and get it merged. I assume this was the only unbound variable problem with ActiveHelp?

[scop]

The only one I happened to hit with my normal usage patterns, yes. I didn't analyze beyond that.