Problem with air where player is standing being replaced rather than the block you are interacting with

So I am trying to make a mod that adds more customization to things like crafting tables and etc.

one of the features is you can take dyed leather and use it to swap out the leather cover of the crafting table to a different color. Here I did a test but instead of replacing the block you are interacting with it places the block where the player is standing.

<blockquote class="imgur-embed-pub" lang="en" data-id="a/kEFvx7k"  ><a href="//imgur.com/a/kEFvx7k">Gif of the error happening</a></blockquote><script async src="//s.imgur.com/min/embed.js" charset="utf-8"></script>

https://i.imgur.com/vPdvj7u.mp4

(Direct link if embed doesnt work)

and here is the script I put in it.

Any suggestions on how to fix this would be appreciated.