required validator does not detect empty arrays, but empty File Lists

[AndyOGo]

We have a multiple choice select list, which ends up being an array.

If it's value is an empty array [] I expect the !value.length check to match, but it is only applied for File Lists.

redux-form-validators/src/presence.js

Line 10 in 3bb1a1f

typeof value === 'string' ? !value.trim() : isFileList(value) && !isNaN(value.length) ? !value.length : !value