Change empty_error type to array. Add tests

[AdRiley]

Pull Request Description

Now empty_error takes a type we can give a more accurate error message here.

I also added some tests and enabled a test that was disabled on windows. (It runs on my windows machine so don't know why it shouldn't be turned on)

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.