How to fix Argument of type 'HTMLElement | null' is not assignable to parameter of type 'HTMLElement'. Type 'null' is not assignable to type 'HTMLElement'.
When you're facing this problem should add a null check. In typescript, you can set that this variable never become null by adding a ! At the end.
Also, you may have the following error Object is possibly 'null'
You can solve by adding ! At the end.
