How do I stop `Omit<User, "nmae">` silently succeeding and removing nothing?

The recipe

type StrictOmit<T, K extends keyof T> = Omit<T, K>

type User = { id: number; name: string; email: string }

type WithoutEmail = StrictOmit<User, 'email'>

The build compiles this and checks each result below.

How it works

1. 01

   type StrictOmit<T, K extends keyof T> = Omit<T, K>

   The entire recipe. The body still delegates to the built-in — only the door is narrower, and the door is where the bug was.

What you get

• WithoutEmail

  →{ id: number; name: string; }

• StrictOmit<User, 'id' | 'name'>

  →{ email: string; }

• Omit<User, 'nmae'>

  →{ email: string; id: number; name: string; }

  The built-in, for comparison: no error, nothing removed, and a type that still looks plausible. This is the bug the constraint prevents.

Where it goes wrong

It is stricter than the built-in in a way that occasionally bites: `Omit` is deliberately permissive so it can be used on unions and on types whose keys are not yet known. Swapping it globally will surface real code that relied on that.