The recently released Lua VM (Luau) does not parse vertical tab characters as whitespace, and throws an error when they are used in source code. Vanilla Lua 5.1 (and beyond) allows vertical tabs for use as whitespace, so Roblox should too for the sake of compatibility.
In order to reproduce this you can run some code with a vertical tab in it. I just ran the default Hello World script but with a vertical tab before it; it ran in Lua 5.1, but not in Luau. Attached is a file that contains exactly that: vertical_tab_test.lua (23 Bytes).
This is obviously very important and I hope Roblox fixes it immediately. Or that it at least gets added to the queue because it is absolutely the least important bug I’ve ever encountered.
We considered supporting this in the initial release, but since vertical tab doesn’t even get its own Wikipedia page (source: Vertical tab - Wikipedia), we decided that it’s not important enough.