Checking JSX elements ignores `JSX.IntrinsicElements` declared using template literal index signatures

[Andarist]

Bug Report

🔎 Search Terms

JSX IntrinsicElements template literal types index signatures

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

declare const React: unknown

declare namespace JSX {
    export interface IntrinsicElements {
        [elemName: `test${string}`]: {}
    }
}

;<testfoo /> // Property 'testfoo' does not exist on type 'JSX.IntrinsicElements'.(2339)

🙁 Actual behavior

An error is reported claiming that testfoo does not exist on type JSX.IntrinsicElements

🙂 Expected behavior

I'd expect that index signature to permit this JSX element.