What does the ! (exclamation mark) operator mean when accessing an object property in TypeScript?

Hi everyone! I recently started learning TypeScript and came across a construct I don't understand. In a colleague's code, I saw the use of an exclamation mark after a variable or before accessing an object property. For example: ```typescript const userName: string | null = getUserName(); const length = userName!.length; ``` Or this variant: ```typescript interface User { name?: string; email?: string; } function getUserEmail(user: User): string { return user.email!; } ``` I understand that `?` means an optional value (can be undefined or null). But what does `!` do? Is it some kind of forced access operator? Won't it cause a runtime error if the value actually turns out to be null or undefined? I tried Googling, but everywhere they write