this is confusing, only seems to occur with an incomplete solution though

Either in or of would work because the keys and values are both the same as each other, but fixed that too.

I see; modified it to use for .. of Object.keys and tested your solution, which works now. :)

Ugh, I swear it worked the first time I tested -
I'll try to figure out the cause of the problem.

Resolved after fixing the above issue.

Republished. Massive oversight on my end, apologies.

I can't seem to replace this.
What code and node version are you using?