fix: Array issue with postRunCommand

[joncrain]

Prefs stored as an array throw an error:

% sudo /Library/Crypt/checkin
panic: interface conversion: interface {} is []string, not string

This should give the option for either a string or an array.

[grahamgilbert]

Fairly certain you're going to still panic here. If the wiki says it's an array, then it should be an array. Remove the cast to string.

[joncrain]

I think you're right that the initial code will not work as expected. However, my concern would be that some people do have this set as a string. The wiki does allow for both it seems:

This preference can either be a string if your command has no spaces, or an array if there are spaces in the command.

So I think it would be best to support both.

[joncrain]

Tested the latest change and it does not panic for string or array and works as expected.

[grahamgilbert]

Looks good. Do you think it would be possible to split this logic out into its out function so there can be unit tests?

[joncrain]

Split the get command and added tests for it.