(a) Is this Table field essentially read-only? If so, you should add a Ui-Only Formula Field and just show that. Then the Formula can determine what content to display in the column.
(b) As of the Brooklyn release, coming out at the end of November, there will be Conditional Rendering of Table Columns so you shouldn’t need to do this at all, you’ll just be able to have 2 / 3 separate Table columns, and Conditionally Render them.
(c) As to the code above, I’m not sure why you’re setting field to the result of a merge, that definitely will be problematic, just set it to the first argument, like this:
var field = arguments[0],
And try that.
