Inferring rest of array in a conditional results in unknown[]

[minhpnz]

Bug Report

🔎 Search Terms

Conditional Array Rest Unknown

🕗 Version & Regression Information

"Bugs" that have existed in TS for a long time are very likely to be FAQs; refer to
#45281

I was unable to test this on prior versions than 4.1

⏯ Playground Link

Playground link with relevant code

💻 Code

type Join<S extends string[], D extends string> =	S extends [] ? '' : S extends [string] ? `${S[0]}` : S extends [string, ...infer R] ? `${S[0]}${D}${Join<R, D>}` : string;

[jcalz]

Um, d..duplicate of #45281. What am I missing here?