Incorrect type in Unreachable code

[RedCMD]

Unreachable code messes up type system

Steps to Reproduce:

1. copy code snippet into TS file
2. notice no errors ✅
   
3. uncomment the 3rd line
4. notice error on last return statement ❌
   

function foo(a: string | undefined): string {
	const b = 'c';
	// return b;
	if (!a) {
		return b;
	}
	return a;
}

my actual code:

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.97.0 (and insiders)
• OS Version: Windows 11

[MartinJohns]

Duplicate of #26914.

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.