How can you capitalize this word in VIM snippet?

EDIT — For those unfamiliar with React, the second “setter” will always begin with set.

I've got the following vim snippet that I'm using (with coc-snippets) for React:

snippet STATE_HOOK "useState hook" b
const [${1:state}, set${1:`!v expand('%:t:r')`}] = useState($2)
endsnippet

This could be used to quickly create the following (incorrect) code:

const [color, setcolor] = useState("green");

The problem is that the setcolor needs to be camelcased, like this: setColor

How would one write this snippet so that the expanded input is capitalized? I've looked at another library's implementation of this, and it looks like this:

const [$1, set${1/\w+\s*/\u$0/g}] = useState(${3:''})${0:;}

However, this provides me with the following:

const [color, set\ucolor] = useState("green");

from How can you capitalize this word in VIM snippet?