More 'undefined' vars checks

[yeeplusplus]

There are three more instances where undefined variables aren't checked in a way that works with the nounset flag

Example (dummy_test):

testDummy() {
  set -o nounset
  cleanupSpies
}

Output:

# dummy_test: 147: eval: _shpy_spies_dir: parameter not set

The other two instances involve createSpy: if a return value is passed via -r, and if no spy name is passed

[codehearts]

I think the remaining undefined variables have been weeded out, is it alright if I close this or do you want to take a second look at this?

[yeeplusplus]

You can close it. Sorry I haven't been as available as I thought I would be.

[codehearts]

It's ok, I really appreciate your contributions and I'm sorry for trampling over your last PR! You actually revealed that shpy wasn't working under some of the shells it claimed to support, and it's motivated me to pay more attention to this project