Return result of shell as string

[JJK96]

I ran into the issue that if I insert the result of a shell command (using !), I get the result as a JSON object.

So I execute the following command: #echo test
And I get the following output:

{"val":"test"}

This PR returns the result of executing a command as a string. So it would return "test" instead.
I don't know why the previous version returned the result as a JSON object, i.e. which usecase it is for. But this solution fits my usecase.

[71]

Ah, good catch; thanks for the PR! I was pretty sure I had already done this, but I guess not. Two changes are necessary to throw errors rather than strings, and it will be good to go.

For reference, the code used those objects because Dance did not correctly support errors in previous versions. It was updated in 0.5, but that specific function was forgotten.