Type 'string | (() => string)' is not assignable to type 'string | number | readonly string[] | undefined'. code example

Example 1: Type 'string | undefined' is not assignable to type 'string'.

let name1:string = person.name as string;

Example 2: Type 'string | undefined' is not assignable to type 'string'.

let name1:string = person.name!; 
//                            ^ note the exclamation mark here