Error on function type that comes from a function declaration that is declared after usage site

[dragomirtitian]

Steps to reproduce

let arr: any[] = [];

// Move fnDeclaration here and it works 
declare let mapFn: typeof fnDeclaration | ((v: any) => number);
// declare let mapFn: ((s: string) => string) | ((v: any) => number); // Also works ok

arr.map(mapFn instanceof Function ? mapFn : i => i); // Error in TS GO


function fnDeclaration(s: string): string {
    return s;
}

Playground Link

Behavior with typescript@5.8

Type checks without errors.

Behavior with tsgo

If fnDeclaration appears after the usage in typeof fnDeclaration we get an error on the arr.map call.

[jakebailey]

Surely this is yet another type ordering problem, since symbols are sorted by declaration location and swapping the order will mean the function sorts earlier...