'?' at the end of a type is not valid TypeScript syntax. Did you mean to write 'number | undefined'?

Object is possibly 'null'.

Argument of type 'number | null' is not assignable to parameter of type 'number'.

Property 'code' is missing in type '{ children: string; dest: string; }' but required in type '{ dest: string; code: boolean; children: string; }'.

Property 'indent' is missing in type '{ children: string; }' but required in type '{ children: string; indent: number | null; }'.